1 
390 


>RLF 


GIFT  OF 
George  Davidson 

1825-1911 


1-annin 


PROFESSOR 


DRY  PLATE  PHOTOGRAPHY; 


OR, 


THE   TANNIN   PROCESS, 

MADE  SIMPLE  AND  PRACTICAL  FOR   OPERATORS  AND 
AMATEURS, 

BY  JOHN    TOWLER,   M.  D.f 

PROFESSOR  OP  NATURAL  PHILOSOPHY,   MATHEMATICS,  AND  CHEMISTRY  IN 

HOBART  COLLEGE ;   AUTHOR  OP   "  THE  SILVER  SUNBEAM,"   «  THK 

AMERICAN  PHOTOGRAPHIC  ALMANAC,"    "THE   PORCELAIN 

PICTURE,"    ETC.  ;    AND    EDITOR    OP    "  HUMPHREY'S 

JOURNAL  OP  PHOTOGRAPHY." 


;  Madidam  vestem  permutare.' 


JOSEPH  H.  LADD,  PUBLISHER,  No.  88  WHITE  STREET. 
LONDON:  TRUBNER  &  CO. 

1865. 


Entered,  according  to  Act  of  Congress,  in  the  year  1865,  by 
JOSEPH  H.   LADD, 

In  the  Clerk's  Office  of  the  District  Court  of  the  United  States  for  the  Southern 
District  of  New  York. 


TR 


TABLE  OP  CONTENTS. 


PAGE. 

INTRODUCTION  .  .  .  .  13 
CHAPTER  I. — PREPARING  THE  PLATES  .  .  .21 
CHAPTER  II. — COATING  THE  PLATES  WITH  COLLODION  31 
CHAPTER  III. — SENSITIZING  THE  PLATES  .  .  .41 
CHAPTER  IV. — EXPOSING,  DEVELOPING,  AND  INTENSI- 
FYING THE  PLATES  ...  54 
CHAPTER  V. — CHANGING  BOXES,  ETC.  —  LANDSCAPE 

PHOTOGRAPHY        .         .         .         .68 
CHAPTER     VI. — PREPARATION  OF  TRANSPARENT  POSI- 
TIVES BY  THE  TANNIN  PROCESS,  OR 
CONTACT-PRINTING  ON  GLASS  .     13 

CHAPTER   VII: — OPAL    PICTURES,    AND   PHOTO-MINIA- 
TURES, BY  THE  DRY  PROCESS         .         84 
CHAPTER  VIII. — DRY  AND  WET  PLATES,  REQUIRING  NO 
SILVER  BATH  ;   OR,   NEGATIVE  PRO- 
CESSES,   WITH   COLLODIO-BROMIDE    OF 

SILVER  92 


INTRODUCTION. 


THE  peculiar  advantages  of  Dry  Plate  Photography 
are  but  little  understood  by  the  ordinary  photographic 
operator  ;  and,  when  these  advantages  are  understood 
and  recognized,  there  is  a  difficulty  in  withdrawing  the 
artist  from  the  general  routine  of  the  wet  process, 
whose  results  are  so  easily  and  quickly  obtained,  flash 
out  as  it  were  in  a  moment  for  adoption  or  condemna- 
tion, to  bestow  his  attention  on  a  process  whose  results 
are  invisible,  and  depend  entirely  upon  the  educated 
experience  of  the  workman  and  the  accuracy  of  his 
workmanship, — a  structure,  in  fine,  built  upon  faith. 

There  is  a  striking  analogy  between  the  two  pro- 
cesses, wet  and  dry,  and  the  two  modes  of  printing, 
direct  solar  printing  and  printing  by  development.  In 
solar  printing  albumen  on  paper,  beneath  a  negative, 
the  image  appears  gradually,  and  finally  assumes  all 
the  necessary  vigor  ;  the  operation  of  printing  can  be 
watched,  controlled,  and  pronounced  finished  when  the 
eye  is  satisfied.  With  a  small  quantity  of  experience 
the  eye  becomes  the  sole  guide.  But  with  development- 
printing  the  image  is  invisible  ;  none  of  our  senses  can 
perceive  its  existence  ;  it  is  a  latent  image  ;  of  this  we ' 
are  firmly  convinced  by  an  experience  that  has  never 
met  with  an  exception  to  the  rule,  we  have  therefore  a 
lively  faith  in  the  result ;  in  the  latter  case,  therefore, 
experience  and  faith  become  our  guides.  They  are 
equally  our  guides  in  dry  plate  photography. 

Nihil  siccisfaucibus  recte  suscipitur,  neque  perficttur, 
I 


14  INTRODUCTION. 

is  an  adage  taken  advantage  of  by  the  intelligent  wet 
process  advocates  ;  but  adages,  like  nostrums,  are  not 
universal  in  their  application  ;  times  and  circumstances 
modify  all  such  deductions.  The  author  of  the  follow- 
ing instructions  in  dry  plate  photography  adheres  tena- 
ciously to  the  wet  process,  admits  its  pre-eminence  in 
general  practice  ;  but  he  is  not  only  willing  to  recog- 
nize advantages  peculiar  to  the  dry  process,  and  ap- 
plicable on  certain  occasions,  but  he  recommends  this 
process  as  the  only  one  to  be  adopted  under  the  cir- 
cumstances in  question. 

Whenever  a  wet  plate  becomes  dry  by  evaporation, 
when  exposed  to  the  view,  before  the  actinic  impres- 
sion is  complete,  the  dry  process  is  to  be  preferred  from 
sheer  necessity ;  for  the  dry  tannin  plate  may  be  ex- 
posed without  deterioration  for  a  whole  day,  a  week, 
or  a  month,  and  until  the  necessary  impression  has 
been  obtained. 

The  practical  operator  will  find  the  dry  process  much 
more  advantageous  than  the  wet  process  in  taking  pho- 
tographs of  public  buildings,  architectural  structures, 
gentlemen's  residences,  country  seats,  farm  houses, 
shipping,  steam  engines,  machinery,  monuments, — in 
fine,  all  works  of  art  and  beauties  of  nature  in  still  life 
in  his  own  city  or  immediate  neighborhood.  Even  if 
the  operator  should  possess  a  portable  tent,  in  the  cases 
just  enumerated  the  dry  plates  are  to  be  preferred  in 
every  instance  whenever  a  picture  of  a  single  building, 
etc.,  alone  is  required.  The  reason  is  almost  self-evi- 
dent. To  hug  or  drag  a  portable  tent  and  camera  to 
the  place  in  question  ;  to  mount  them  on  tripods  for 
operation ;  to  place  the  collodion  bottle,  the  bottle  con- 
taining the  developer,  the  water  bottle,  and  the  bottle 
holding  the  fixing  solution,  each  in  order ;  to  expose, 
develop,  fix,  wash  the  plate,  and  stow  it  away  in  a  safe 


INTRODUCTION.  15 

place  where  no  accident  can  befal  it ;  to  pack  up  again 
all  these  paraphernalia  and  retrace,  with  bag  and  bag- 
gage, the  homeward  path — all  these  operations  contrast 
very  distinctly  with  that  of  carrying  on  the  shoulder  a 
small  camera  already  screwed  to  its  tripod,  and  ready 
for  operation  the  moment  the  goal  is  attained.  The 
camera  is  lowered,  the  view  adjusted  in  focus,  the  pic- 
ture taken  before  an  accumulation  of  human  young- 
sters can  stop  up  the  aperture  of  the  lens  or  diversify 
the  scene  on  the  collodion  plate  with  innumerable  ghosts. 
The  camera  came  and  is  gone  before  the  inquisitive 
have  had  time  to  ascertain  the  cause  of  your  appearance 
and  departure. 

The  same  advantage  is  manifest  on  the  side  of  dry 
plate  photography  whenever  an  indefinite  number  of 
views  have  to  be  taken  in  a  city,  each  one  remote  from 
the  rest.  In  this  case  the  whole  burden  consists  of  a 
camera,  tripod,  and  a  changing  box. 

The  dry  process,  in  the  cases  enumerated,  requires 
but  one  operator.  The  wet  process  would  require  at 
least  two. 

The  amateur  photographer  and  the  tourist  will  inva- 
riably give  preference  to  the  dry  process.  Even  while 
the  train  stops  at  the  station,  or  the  steamboat  at  the 
landing,  the  energetic  tourist  has  time  and  facilities  by 
this  process  to  carry  away  a  picture,  a  visible  reminis- 
cence of  towns  and  harbors,  which  may  serve  to  illus- 
trate his  diary  or  give  pictorial  beauty  to  his  corre- 
spondence. With  the  wet  traps  he  can  accomplish 
nothing  of  the  kind  ;  neither  the  train  nor  the  steamer 
waits  for  any  man  beyond  the  appointed  four  or  five 
minutes,  which  are  quite  sufficient  for  an  actinic  im- 
pression, but  not  to  mount  and  remount  a  photographic 
dark  chamber.  While  other  indifferent  travelers  step 
on  shore  or  on  land  to  straighten  their  legs  or  wet  their 


16  INTRODUCTION. 

whistles,  our  tourist,  philosopher,  and  poet,  with  quick 
eye,  has  already  discriminated  the  beauties  he  wishes 
to  depict  before  he  dismounts,  now  marches  to  the  de- 
sired point,  adjusts  the  lens  to  focus,  counts  the  time, 
and  is  already  again  in  his  seat  before  his  neighbors 
have  had  time  to  slacken  their  crural  extensors  or 
modify  their  pharyngial  passages.  This  is  taking  pic- 
tures on  the  wing. 

Finally,  transparent  positives,  opal  or  porcelain  pic- 
tures, transparent  stereographs,  and  photo-miniatures 
are  very  easily  and  beautifully  prepared  on  dry  plates, 
sometimes  more  easily  than  on  wet  plates,  and  in  some 
instances  where  it  is  impossible  to  take  them  at  all  by 
means  of  wet  plates.  To  print  on  glass,  that  is,  on 
dry  plates,  has  become  one  of  the  most  enchanting 
operations  in  photography,  as  an  evening  recreation  by 
gaslight.  This  light,  or  the  light  from  a  small  piece  of 
burning  phosphorus,  or  a  few  spirals  of  magnesium 
wire,  is  quite  intense  enough  to  produce  the  required 
actinic  effect  on  a  dry  plate  in  a  few  minutes.  Dur- 
ing the  summer  season — the  season  for  trips  and 
excursions — negatives  accumulate  to  a  great  extent, 
and  remain  on  hand  unprinted  until  the  dreary  winter 
arrives,  when  nature  lies  buried  in  sepulchres,  as  it 
were,  clothed  in  white  raiment,  and  when  homes  be- 
come irksome  without  employment ;  now  is  the  time, 
in  the  long  evenings,  with  our  wife  and  children  around 
us,  to  bring  the  negatives  from  their  niches,  take  im- 
pressions of  each  by  the  dazzling  jet  of  light  from  the 
argand  burner  on  the  table,  and  recount  to  them,  in  the 
midst  of  such  vivid  illustrations,  the  stories  and  his- 
tories arising  from  scenes  visited  or  renowned.  This 
source  of  innocent  and  instructive  pleasure  is  inexhaust- 
ible, its  enchantment  can  not  be  described  ;  it  can  be 
understood  only  by  those  who  have  participated  in  it. 


INTRODUCTION.  17 

A  friend  of  ours,  the  other  day,  in  all  earnestness  as- 
serted that  if  the  dry  process  did  not  exist,  or  some 
equivalent  process,  he  should  forego  photography  and 
procure  himself  a  lathe  with  a  slide  rest  and  eccentric 
chuck,  and  take  to  turning  cycloidal  gyrations  in  box- 
wood. Such  an  expression  as  this  is  totally  unintelli- 
gible jto  a  common  operator  with  the  wet  plate  process. 
Let  him,  however,  be  able  in  the  evening,  with  his  dear 
ones  around  him,  to  prosecute  gaslight  photography 
on  dry  plates ;  he  will  be  carried  away  with  the  ravish- 
ing pastime,  and  with  Milton  he  will  exclaim  :  "  Into 
the  heaven  of  heavens  I  have  presumed,  and  drawn  em- 
pyreal air." 

Photographers  in  general  have  hitherto  been  deterred 
from  trying  experiments  with  dry  plate  photography 
from  the  circuitous  mode  of  preparing  the  plates,  from 
the  tendency  of  the  film  to  peel  off  in  the  very  midst  of 
the  development,  or  in  the  final  washing,  or  from  the 
want  of  success  in  securing  a  picture. 

If  we  can  teach  a  method  of  preparing  dry  plates  that 
shall  deviate  very  little  from  that  of  preparing  wet 
plates,  we  hope  to  be  able  to  enlist  many  of  our  practic- 
al men  to  take  up  this  useful  and  beautiful  branch  of 
the  photographic  art.  It  is  our  belief  that  such  instruc- 
tion can  be  given.  Thus,  the  plate  is  prepared  exactly 
in  the  same  manner  as  for  the  wet  process  ;  it  receives 
the  same  substratum  of  albumen,  is  coated  with  the 
same  collodion,  sensitized  in  the  same  silver  bath, 
washed  at  the  tap  like  an  ordinary  negative,  and  in 
other  respects  treated  in  a  very  simple  way.  We  do 
not  maintain  that  this  is  the  best  method^nor  do  we 
presume  to  teach  the  best  method  ;  but  we  flatter  our- 
selves with  the  belief  that  the  method  here  explained 
will  be  as  successful  in  the  hands  c  *  others  as  it  is  in- 
variably in  our  own,  naturally  on  the  single  condition 


18  INTRODUCTION. 

that  our  scholars  are  obedient  and  observant  of  all  the 
rules  we  prescribe. 

The  developer,  too,  is  the  ordinary  pyrogallic  devel- 
oper or  intensifier  of  the  wet  plate.  With  such  sim- 
plicity of  operation  failure  can  scarcely  occur. 

The  tendency  of  the  film  to  split  up  or  peel  off  is  en- 
tirely obviated  by  the  previous  substratum  of  dilute 
albumen  ;  and  when  the  pupil  is  sufficiently  advanced 
and  experienced,  even  this  substratum  can  be  omitted, 
with  the  exception  on  the  edges. 

The  want  of  success  in  securing  a  picture  on  a  dry 
plate  has  arisen  principally  from  impatience  and  hurry, 
and  the  aim  of  dry  plate  photographers,  being  to  shorten 
the  time  of  exposure,  has  all  along  conduced  to  hurl 
beginners  into  the  trouble  alluded  to.  Be  convinced 
that  the  sensitiveness  of  a  dry  plate  is  far  inferior  to 
that  of  a  wet  plate,  five  or  six  times  less,  that  is,  if  a 
given  lens  with  a  given  stop,  light,  and  exposure,  will 
produce  a  picture  on  a  wet  plate  in  twenty  seconds,  the 
same  lens  will  require,  under  the  same  conditions  on  a 
dry  plate,  about  two  minutes  at  least,  and  most  prob- 
ably four  minutes'  exposure  would  be  no  injury  to  the 
result  sought.  Do  not  be  beguiled  by  any  assertion  of 
others,  or  any  desire  of  your  own  to  diminish  the  time 
of  exposure  ;  you  will  fail  assuredly  if  you  do,  and  will 
then  condemn  a  good  process.  The  dry  plate  requires 
a  long  exposure ;  and  learn  now  that  over-exposure  is 
no  injury,  because  there  are  means  of  controlling  its 
effects,  but  there  are  no  means  of  remedying  an  under- 
exposed dry  plate,  that  is,  of  getting  a  picture  on  a  film 
where  light  has  failed  itself  to  perform  it's  part  of  the 
wonderful  task.  It  is  true  that  the  alkaline  developer, 
as  it  is  called,  has  a  tendency  to  shorten  the  long  expo- 
sure, but  it  increases  in  the  same  ratio  the  chances  of 
failure  ;  and  although  we  ourselves  are  delighted  with 


INTRODUCTION.  19 

the  results  of  the  alkaline  developer,  as  well  as  with  an 
alkaline  treatment  of  the  dry  plate  previous  to  expo- 
sure, we  recommend  it  to  our  scholars  not  as  a  normal 
practice,  but  rather  as  a  means  to  be  adopted  if  we 
know  beforehand  that  the  time  of  exposure,  by  what- 
ever circumstances,  was  too  short. 

Our  older  and  more  experienced  readers  may  be  in- 
clined to  think  that  a  long  exposure  gives  room  for 
great  disturbances  in  the  picture  by  means  of  the  wind 
or  waves  ;  such  an  idea  is  very  natural,  but  our  friend, 
Mr.  Hull,  one  of  the  most  successful  of  amateur  dry  plate 
photographers  in  the  city  of  New  York,  has  set  us  to 
rights  on  this  score  by  the  results  of  his  experience, 
which  manifestly  shows  that  there  is  no  more  disturb- 
ance produced  by  the  wind  during  a  long  exposure  on  a 
dry  plate,  than  by  the  same  cause  during  a  short  expo- 
sure on  a  wet  plate  ;  furthermore,  our  own  experience 
proves  indisputably,  that  a  cause  which  would  be  ruin- 
ous to  a  wet  plate  would  be  scarcely  perceptible  on  a  dry 
plate.  Thus,  a  carriage  moving  slowly  along  the  street, 
would  certainly  spoil  the  picture  on  a  wet  plate,  by 
producing  a  feeble  image  of  the  vehicle  as  it  moved 
along ;  whereas,  on  the  dry  plate  the  result  most 
probably  would  be  imperceptible. 

But  we  have  before  observed  that  the  province  of  dry 
plate  photography  is  properly  with  still  life,  where  the 
wind  and  the  waves  have  no  influence  in  producing 
motion,  and  where  success  is  most  certain.  Keeping, 
therefore, v dry  plate  photography  within  its  prescribed 
limits,  we  have  no  hesitation  in  asserting  and  believing 
that  the  results  of  success  with  this  process  will  be 
more  numerous  than  with  the  wet  process,  and  that  the 
labor  required  to  produce  these  results  will  be  much 
less  by  the  former  process  than  by  the  latter.  Having 
made  these  few  introductory  remarks,  which  we  deemed 


20  INTRODUCTION. 

necessary,  in  order  to  institute  a  right  sort  of  feeling  on 
the  subject  and  acquaintance  with  it  at  the  outset,  we 
shall  now  proceed  to  our  pleasant  task  of  once  more  im- 
parting instruction  on  a  subject  which  forms  a  part  of 
our  practice,  and  which  we  hope  to  improve  by  teaching  : 

Discimus  docendo. 


CHAPTER  I. 

PREPARING  THE  PLATES. 

IT  is  desirable  in  dry  plate  photography  to  make  use 
of  flattened  plate-glass,  because  it  will  frequently  hap- 
pen that  you  may  desire  to  take  transparent  copies  of 
your  negatives  on  dry  plates.  Jn  this  case,  the  two  sur- 
faces, that  is,  the  surface  of  the  negative  and  that  of 
the  dry  plate,  which  is  intended  to  receive  the  picture, 
must  be  accurately  in  contact  in  every  part.  With 
common  glass  this  condition  can  seldom  or  never  be  at- 
tained. The  glass  must  be  free  from  all  sorts  of  flaws 
or  imperfections,  because  it  would  be  a  great  loss  ofc 
time  and  material  to  go  to  the  trouble  of  preparing  a 
dry  plate,  and  know  beforehand  that  the  result,  nine 
times  out  of  ten,  with  such  imperfections  staring  you 
in  the  face,  must  inevitably  be  imperfect.  Some  dry 
plate  photographers  are  so  particular  in  regard  to  their 
glass,  as  never  to  use  a  plate  that  has  already  been 
once  coated  with  the  sensitive  substances.  This  degree 
of  refinement  and  care  is,  in  our  opinion,  unnecessary, 
although  we  are  willing  to  admit  that  better  results  are 
more  likely  to  be  obtained  by  such  a  precaution,  and 
the  ordinary  mode  of  cleaning  glass,  than  by  using 
old  plates  over  again ;  but  if  old  plates  be  cleaned  in 
the  manner  hereafter  described,  they  may  be  coated 
several  times  in  succession  without  any  detriment  to 
success. 

Each  plate  is  cut,  with  the  diamond,  of  the  required 
length  and  breadth,  and  the  sharp  edges  are  carefully 
filed  or  ground  off  on  a  grindstone.  The  latter  method  is 


22  DRY   PLATE  PHOTOGRAPHY  J    OR, 

by  far  the  neatest  and  most  expeditious,  if  a  grindstone 
is  conveniently  at  hand.  Such  a  grindstone  as  is  used 
by  jewelers  and  dentists,  and  turned  by  a  treddle  in  a 
lathe,  is  exceedingly  well  adapted  for  this  purpose.  For 
some  of  the  changing  boxes  in  the  market  it  is  neces- 
sary, furthermore,  to  cut  off  the  four  corners  of  the 
plate,  and  then  grind  them  round,  so  as  to  present  no 
impediment  to  the  sliding  of  the  plate  out  of  the  chang- 
ing box  into  the  plate-holder,  and  then  back  again  into 

the  changing  box  after  exposure.     The  / 

plate,  so  far  prepared  has  the  following 
appearance :  V 

Other  changing  boxes,  on  the  contrary,  by  reason  of  a 
different  construction,  do  not  require  anything  more  to 
be  done  to  the  plates  than  to  cut  them  into  a  rectangu- 
lar shape,  and  to  abrade  the  edges,  as  in  the  preparation 
.of  wet  plates. 

The  plates  at  this  stage  are  now  immersed  in  a  pail 
of  clean  water,  and  left  there  for  half  an  hour  or  so. 
Each  one  is  then  taken  out,  washed  on  either  surface 
with  a  clean  sponge,  again  immersed  and  washed,  until 
the  two  surfaces  are  perfectly  transparent  and  clean. 
Finally  the  plate  is  well  agitated  in  fresh  water,  and 
then  immediately  submitted  to  the  next  operation,  which 
consists  in  coating  one  surface  with  a  solution  of  albu- 
men, as  hereafter  described. 

When  plates  have  been  used  before,  and  are  still 
covered  with  collodion  and  varnished,  another  treatment 
is  necessary.  In  this  case  the  negatives  are  placed  in 
a  glass  or  porcelain  vessel  containing  twenty  parts  of 
water  and  one  part  of  nitric  acid,  and  raised  to  the  boil- 
ing temperature,  when  it  will  be  found  that  the  collo- 
dion film  and  varnish  will  immediately  separate  from 
the  glass.  A  stronger  bath  of  nitric  acid  at  a  low  tem- 
perature will  subserve  the  same  purpose.  Be  careful  in 


THE   TANNIN   PROCESS.  3d 

manipulating  with  a  strong  solution  of  this  acid  to 
avoid  getting  the  acid  on  the  hands  or  clothes  ;  this 
object  is  easily  attained  by  using  slips  of  glass  for 
raising  the  plates  out  of  the  bath. 

Carey  Lea's  bath  for  removing  collodion  films  or  im- 
purities from  glass  plates  is  most  excellent ;  we  use  it 
invariably  in  our  laboratory  for  the  purpose  in  question, 
and  frequently  we  throw  in  new  plates  of  glass,  whereby 
all  rust  appears  to  be  removed,  and  the  surfaces  are 
rendered  beautifully  clean.  This  bath  is  highly  to 
recommended,  and  is  prepared  as  follows  : 

Bichromate  of  potash    ...       1  ounce. 
Sulphuric  acid  .  1  ounce. 

Water 16  ounces. 

As  soon  as  the  salt  is  dissolved,  the  bath  is  ready  to 
receive  the  old  plates  ;  these  are  allowed  to  remain  sev- 
eral hours  in  the  bath,  which  separates  the  films  and 
removes  extraneous  substances  from  the  surfaces.  The 
bath  can  be  used  over  and  over  again,  for  a  long  time  ; 
it  may  be  strengthened  from  time  to  time  by  the  addi- 
tion of  fresh  crystals  of  bichromate  and  of  sulphuric  acid. 

The  plates  are  raised  from  this  bath  in  like  manner, 
by  means  of  slips  of  glass  ;  they  are  then  allowed  to 
drain  for  a  moment,  and  finally  thoroughly  washed  in 
pure  water,  and  placed  on  the  draining  racks  to  dry,  if 
the  surfaces  are  intended  to  be  polished  afterward  ; 
otherwise  each  is  ready  as  soon  as  it  is  washed  to  re- 
ceive the  substratum  of  albumen,  which  is  prepared  as 
follows  : 

Separate  the  white  of  a  single  egg  from  the  yolk,  and 
beat  it  well  up  into  a  froth,  then  add  to  the  froth  six 
ounces  of  pure  rain  or  distilled  water  and  one  drachm 
of  ammonia.  Shake  the  mixture  very  intimately  to- 
gether in  a  bottle,  which  must  contain  at  least  twice  the 


24 

quantity  of  material,  that  is,  about  a  pint  measure.  The 
solution  is  next  filtered  through  a  tuft  of  cotton  wool  ; 
it  might  be  filtered  through  coarse  filtering  paper,  only 
in  this  case  the  solution  assumes  a  very  slight  tinge  of 
straw  color  in  passing  through  the  paper.  This  arises 
probably  from  the  fact  that  the  sizing  of  the  paper  is 
dissolved  by  the  ammonia.  It  is  preferable  to  avoid 
this  coloration,  by  using  only  a  clean  tuft  of  cotton  in- 
serted in  the  neck  of  the  filter.  The  first  part  of  the 
solution,  to  the  amount  of  about  an  ounce,  is  poured 
back  again  into  the  filter,  because  it  probably  has  taken 
down  with  it  a  few  fibres  of  cotton,  which  would  be  in- 
jurious in  the  subsequent  operations,  if  left  on  the  film. 
The  vessel,  too,  which  receives  the  filtrate  at  this  stage 
is  carefully  washed  out  with  clean  water,  and  the  filtra- 
tion is  allowed  to  proceed  to  the  conclusion. 

The  plate  having  been  well  washed,  as  already  de- 
scribed, is  either  fixed  on  a  pneumatic  holder,  or  held 
by  one  corner,  between  the  thumb  and  forefinger,  as  a 
plate  is  held  for  the  reception  of  collodion.  The  albu- 
men solution  is  then  poured  upon  the  extreme  right- 
hand  corner,  and  is  allowed  to  flow,  sidewise  to  the 
distant  left-hand  corner,  and  then  downward  toward 
the  hand,  driving  before  it  the  moisture  still  adhering  to 
the  surface,  and  passing  off  at  the  nearest  right-hand 
corner,  into  the  vial  containing  the  solution.  It  fre- 
quently happens  during  filtration  that  innumerable 
small  air  bubbles  are  formed  on  the  surface  of  the  fil- 
trate; this  may  partially  be  avoided  by  dipping  the 
beak  of  the  glass  filter  into  the  solution,  or  by  not 
allowing  the  solution  to  fall  more  than  half  an  inch  or 
so  before  it  reaches  the  vessel  beneath.  Should  it  so 
happen,  however,  that  the  albumen  solution  contains  a 
quantity  of  these  air  bubbles,  they  must  be  blown  away 
to  the  opposite  side  of  the  vessel  before  you  begin  to 


THE  TANNIN   PROCESS.  25 

pour  the  solution  upon  the  plate  ;  otherwise,  if  you  once 
get  them  upon  the  plate,  you  can  rarely  get  rid  of  them 
without  flowing  the  plate  two  or  three  times,  a  process 
which  is  likely  to  produce  an  uneven  film  and  to  gener- 
ate a  fresh  crop  of  bubbles.  In  pouring  the  solution 
upon  the  plate,  it  is  advisable  to  place  the  spout  of  the 
vessel  near  the  surface  of  the  plate,  in  order  thus  to 
obviate  as  much  as  possible  the  generation  of  these 
offensive  bubbles,  which  if  left  on  the  film  will  produce 
transparent  circles  in  the  picture,  visible  after  all  the 
operations  are  ended.  To  coat  the  plate  evenly  and 
uniformly  requires  gentleness  of  action  combined  with 
the  preceding  directions ;  a  quick  and  boisterous  de- 
meanor will  not  succeed  at  all. 

Another  mode  of  coating  plates,  and  one  which  is 
generally  used  when  the  plates 'are  dried  and  polished, 
is  the  following : 

Place  at  the  bottom  of  a  clean,  flat  porcelain  dish, 
along  either  end,  a  slip  of  glass  of  about  half  an  inch  in 
width,  and  then  pour  into  the  dish  a  sufficient  quantity 
of  the  albumen  solution,  so  as  just  to  cover  the  slips  of 
glass.  Now  taking  in  the  hand  a  plate  of  glass  which 
has  been  already  washed  and  polished,  let  one  end  rest 
upon  one  of  the  slips  of  glass,  and  gradually  and  slowly 
incline  the  plate  down  upon  the  solution,  carrying  thus 
all  bubbles  before  it  as  it  sinks,  until,  finally,  the  other 
end  rests  upon  the  other  slip  of  glass.  The  solution  in 
the  dish  must  not  be  high  enough  to  cover  the  plate  as 
it  now  lies  on  the  slips  of  glass,  but  simply  to  moisten 
the  under  surface  completely.  The  plate  is  now  gently 
raised  out  of  the  solution,  by  means  of  another  slip  of 
glass,  allowed  to  drain  by  resting  one  corner  on  one  of 
the  glass  slips  in  the  dish,  and  then  reared  away  to  dry 
on  the  rack.  There  are  various  ways  of  making  these 
drying  racks  ;  we  will  describe  one  which  we  use  our- 


36  DRY  PLATE  PHOTOGRAPHY  ;    OR, 

selves.  It  has  the  following  appearance  :  It  is  con- 
structed of  four  pieces  of  half  inch  stuff,  of  the  follow- 
ing shape  and  size  ;  16  inches  long,  and  contains  28 
dentations. 


The  figure  of  the  drying  rack  will  show  how  the  four 
pieces  are  to  be  tacked  together.  It  will  be  observed 
that  the  dentations  upon  which  the  plates  rest  are  not 
rectangular,  but  triangular  <  the  object  of  this  con- 
struction is  to  place  the  albumen  or  collodion  film  on 
the  side  looking  toward  the  inclined  side  of  the  den- 
tation, whereby  it  will  be  prevented  from  any  injury 
from  friction  ;  whereas,  if  the  edge  were  perpendicular, 
the  collodion  film  would  be  sure  to  suffer.  A  number 
of  these  racks  will  be  found  very  useful,  in  fact,  in- 
dispensable ;  hence  the  minuteness  of  the  description, 
in  order  that  the  operator  jnay  construct  or  have  con- 
structed a  proper  number  at  the  beginning,  and  thus 
save  himself  much  trouble  afterward,  which  would 
inevitably  ensue  without  them.  After  being  carefully 
polished  with  sand-paper,  they  are  coated  with  two  or 
three  coats  of  varnish,  and  when  dry  are  ready  for  use. 

When  the  albumen  film  is  quite  dry,  it  is  hard  and 
transparent ;  and  the  albumenized  surface  is  almost 


THE  TANNIN  PROCESS.  *  » 

indistinguishable  from  the  glass.  By  taking  care  to 
place  the  albumenized  surface  always  toward  the  in- 
clined plane  of  the  dentation  you  will  have  no  trouble 
in  recognizing  which  surface  has  to  be  coated  with 
collodion. 

This  film  of  albumen  adheres  with  great  tenacity  both 
to  the  glass  and  to  the  collodion  which  is  afterward 
poured  upon  it,  and  thus  prevents  the  collodion  film 
from  ever  slipping  or  peeling  off.  In  consequence  of 
this  we  recommend  you  for  some  time  to  follow  the  plan 
here  described  of  coating  the  glass  with  albumen  ;  but 
as  soon  as  you  are  quite  conversant  with  all  the  manip- 
ulations of  dry  plate  photographic  manipulations,  you 
may  abandon  this  plan,  and  resort  to  the  following 
expedient  for  subserving  the  same  purpose,  but  with 
more  care. 

The  same  albumen  solution  is  used  here  as  before  ; 
and  let  me  remark,  that  where  the  solution  is  to  be 
preserved  for  future  use  it  is  well  to  throw  into  the 
vial  a  few  particles  of  camphor,  to  prevent  decomposi- 
tion. 

Procure  a  camel's  hair  pencil  and  a  handle  to  insert 
it  on.  Tie  the  pencil  to  the  handle,  by  means  of  silk 
thread,  in  such  a  manner  that  the  handle  and  the  pencil 
lie  side  by  side,  the  end  of  the  former  projecting  about 
a  quarter  of  an  inch  beyond  the  hairs  of  the  latter. 
Now  dip  this  end  of  the  combination  into  the  albumen 
solution  ;  a  small  quantity  will  adhere  to  the  pencil. 
Resting  the  projecting  end  against  the  edge  of  the 
polished  plate,  and  allowing  the  wet  pencil  to  touch  the 
surface  of  the  plate,  press  gently  upon  it  and  proceed 
from  one  end  to  the  other,  leaving  thus  a  streak  of  the 
albumen  along  the  surface.  The  object  of  the  project- 
ing end  of  the  handle  is  to  prevent  the  pencil  from 
making  too  brpad  a  streak  ;  if  the  latter  is  three-six- 


28  DRY  PLATE  PHOTOGRAPHY  ;   OR, 

teenths  of  an  inch  in  width,  the  protection  to  the  collo- 
dion film  will  be  sufficiently  assured.  Varnish  each  edge 
of  the  plate  in  the  same  way  all  round.  The  plates 
thus  prepared  with  a  streak  of  albumen  on  each  edge 
are  reared  as  before  on  the  drying  rack,  and  in  the 
same  manner  in  reference  to  the  albumenized  edges  and 
the  inclined  plane  of  the  dentations,  so  that  there  may 
be  no  mistake  in  coating  the  unvarnished  side  after- 
ward with  collodion. 

Some  photographers  postpone  this  varnishing  of  the 
edges  until  the  plates  have  been  coated  with  collodion, 
sensitized,  and  exposed.  It  is  certainly  not  so  conveni- 
ent then  as  now ;  and,  consequently,  we  advise  our 
readers  to  pursue  the  plan  prescribed. 

Other  solutions,  too,  are  frequently  used  instead  of 
albumen;  such,  for  instance,  as  india-rubber  dissolved  in 
benzole  or  in  chloroform,  as  also  solutions  of  gelatine, 
etc.  The  latter  we  have  used  and  become  thoroughly 
disgusted  with  it,  because  it  is  so  apt  to  undergo  a  sort 
of  fermentation,  by  which  the  collodion  picture  develops 
in  a  most  horrid  manner.  The  former  solutions  may 
be  recommended  merely  as  a  variety  in  the  manipu- 
lation. 

The  india-rubber  solution  is  made  by  soaking  a  grain 
of  this  substance  in  sheets  in  one  ounce  of  benzole  for  a 
day  or  two.  The  india-rubber  is  cut  up  into  very  small 
slices  to  aid  the  solution ;  and  the  mixture  is  shaken  every 
now  and  then  for  the  same  purpose.  When  convenient, 
the  mixture  is  filtered  several  times  through  fresh  fil- 
tering paper,  when  the  solution  will  he  found  ready  for 
use.  Before  the  plates  are  coated  with  this  liquid,  they 
are  thoroughly  dried  over  a  flame,  or  at  the  stove,  and 
then  allowed  to  cool  again.  The  solution  is  poured 
upon  the  surface  like  collodion,  and  the  film  is  dried 
gently  by  artificial  heat,  and  the  plate  is  then  put  away 


THE  TANNIN   PROCESS.  29 

for  the  next  operation.    The  following  solution  is  also 

recommended  for  the  same  purpose  : 

India-rubber   .        .        .        .        .2  grains. 
Amber        .        .        .        ,        .         1       " 
Chloroform      .        ...        .4  drachms. 

.  Soak,  dissolve,  and  filter  as  before.  This  solution  dries 
more  readily  than  the  preceding.  Where  india-rubber 
solution  is  used,  the  plates  soon  dry  and  are  quickly 
ready  to  be  coated  with  collodion  ;  whereas,  if  a  solu- 
tion of  gelatine  or  of  albumen  is  employed,  the  films  do 
not  dry  so  quickly,  and  the  operation  is  thereby  im- 
peded. The  solution  of  gelatine  recommended  for  this 
purpose  is  prepared  as  follows  : 

Prepared  gelatine         .        .        .20  grains. 

Water       .        .        .  -  .          8  ounces. 

Glacial  acetic  acid        ...      5  drops. 

Soak  the  gelatine  for  a  few  hours  in  the  water,  then 
dissolve  by  heat,  and  filter  several  times  through  a 
moist  filter.  The  plates  may  be  coated  with  this  solu- 
tion in  the  manner  already  recommended  for  the  albu- 
men solution.  To  obviate  the  troubles  which  arise 
from  the  use  of  a  gelatine  substratum,  and  to  produce 
at  the  same  time  a  very  tenacious  film,  it  has  been 
found  advisable  to  coat  the  gelatine  film  with  one  of  the 
india-rubber  solutions  just  described. 

We  have  mentioned  a  number  of  the  solutions  used 
in  the  preparation  of  dry  plates,  but  do  ncft  use  any 
other  ourselves  than  the  one  first  described,  that  is,  the 
albumen  solution  ;  and  even  this  we  frequently  dis- 
pense with  excepting  to  varnish  the  edges  before  the 
plates  are  coated  with  collodion. 

For  this  purpose  the  plates  are  polished  after  they 
have  been  carefully  washed  and  dried.  The  plate  is 
fixed  in  the  vise  in  such  a  manner  that  the  upper  sur- 


30  DRY  PLATE  PHOTOGRAPHY. 

face  stands  slightly  above  the  ledges  of  the  vise  that 
holds  it.  A  little  rotten-stone  is  then  dusted  upon  the 
surface,  and  a  few  drops  of  alcohol  are  poured  upon  the 
dust  ;  the  mixture  is  intimately  rubbed  over  every  part 
by  means  of  a  large  velvet  cork  covered  with  Canton- 
flannel,  or  wash-leather.  When  the  surface  is  dry,  the 
extraneous  powder  is  rubbed  off  with  a  piece  of  clean 
Canton-flannel,  and  then  the  surface  is  well  polished  with 
a  large  cork  covered  with  soft  chamois  leather.  Fi- 
nally, breathe  upon  the  surface  ;  if  the  film  of  breath  is 
uniform  and  free  from  lines  or  curves,  the  glass  is 
properly  polished  ;  if  not,  breathe  again  upon  the  sur- 
face and  polish  it  with  the  chamois  rubber  ;  repeat  the 
operation  until  uniformity  in  the  breath  film  has  been 
attained. 

Finally,  to  sum  up  our  instructions  in  this  chapter, 
follow  minutely  the  following  order  : 

1.  Cut  out  the  plates  and  abrade  the  edges. 

2.  Place  them  in  the  bichromate  bath,  if  necessary. 

3.  Wash  them  thoroughly,  and  coat  with  the  albumen 
solution,  or, 

4.  If  the  edges,  alone  are  to  be  varnished  place  the 
plates  in  the  draining  stand  to  dry,  then  polish  the 
plates  and  varnish  the  edges  as  described. 

In  all  these  operations  the  utmost  c^anliness  is  re- 
quired, and  the  room  must  be  kept  as  free  as  possible 
from  dust.  This  is  effected  by  first  dusting  and  spong- 
ing the  shelves,  etc.,  with  a  moist  sponge,  then  sprinkling 
the  floor  with  water. 

The  plates  being  all  covered  on  one  surface  with  a 
substratum  of  albumen,  or  varnished  around  the  edges, 
and  placed  in  readiness  on  the  drying  rack,  we  are  now 
ready  for  the  next  operation  in  order. 


CHAPTER  II. 


THE  negative  collodion  sold  by  any  of  our  large  pho- 
tographic establishments  in  the  city  will  be  suitable  for 
the  preparation  of  dry  plates.  It  is  not  maintained  that 
the  most  sensitive  film  can  be  obtained  by  any  of  them  ; 
but  we  have  used  all  of  them,  and  find  that  dry  plates 
can  be  prepared  with  them  that  will  answer  the  pur- 
poses intended.  If  we  manufacture  our  own  collodion, 
which  is  seldom  the  case,  we  use  the  following  formula  : 

COLLODION  FOR  DRY  PLATES. 


No.  1. 


Alcohol          .        , 
Ether 

Pyroxyline    . 
Bromide  of  cadmium 
Iodide  of  ammonium 


10  ounces, 

10  ounces. 

120  grains  i 

100  grains. 

60  grains. 


'  more  Jf  \ 
.required,/- 


No.  2. 


OR, 

Alcohol 
Ether 

Pyroxyline    . 
Iodide  of  ammonium 
Iodide  of  cadmium 
Bromide  of  cadmium 


10  ounces. 
10  ounces. 
120  grains  (, 
80  grains. 
40  grains. 
40  grains. 

Separate  the  cotton  into  small  tufts  or  flocks,  and  in- 
troduce them  into  the  ether,  then  pulverize  the  salts  in 
a  clean  mortar  and  dissolve  them  in  the  alcohol ;  finally, 
add  the  two  mixtures  together,  shake  intimately,  and 
set  the  solution  aside  for  a  day  or  two  to  settle.  The 
collodion  must  now  be  filtered,  and  is  then  ready  for  use. 

Before  you  proceed  to  coat  a  prepared  plate  with  this 
collodion  it  is  necessary  first  to  try  its  working  powers. 


32  DRY  PLATE  PHOTOGRAPHY  J   OR, 

Coat  an  ordinary  polished  plate  with  the  collodion,  and 
see  whether  it  flows  easily  over  the  plate,  and  possesses 
at  the  same  time  a  sufficient  amount  of  consistency  as 
to  form  a  tolerably  thick  film  without  producing  a  re- 
ticulated surface  ;  if  this  be  so,  there  is  no  doubt  a  suffi- 
ciency of  pyroxylme  in  the  collodion.  If,  on  the  con- 
trary, the  collodion  flows  almost  like  alcohol  or  water, 
the  film  will  not  be  suitable  for  a  dry  plate.  Having 
obtained  a  proper  degree  of  consistency,  allow  the  film 
to  dry  on  the  plate.  If  when  dry  the  film  is  transparent 
and  almost  und?stinguishable  from  the  glass,  it  is  suit- 
able for  the  preparation  of  a  dry  plate.  If,  on  the  other 
hand,  the  dry  film  is  opaque  or  opalescent,  the  resulting 
picture,  on  a  plate  prepared  with  such  collodion,  will 
not  be  normally  good,  and  it  is  better  not  to  lose  your 
time  in  the  preparation  of  plates  which  it  is  known 
beforehand  will  not  yield  the  best  results. 

When  the  collodion  film  is  opaque  after  drying,  the 
pyroxylme,  most  likely,  is  in  fault,  if  you  know  certainly 
that  the  alcohol  and  ether  are  as  nearly  absolute  as 
can  ordinarily  be  obtained.  Should  the  latter,  however, 
be  dilute,  they  of  themselves,  in  such  a  condition,  will 
be  sufficient  to  produce  the  opalescence  alluded  to. 

After  you  have  ascertained  that  the  collodion  is 
capable  of  producing  a  shining,  transparent  film,  it  is 
necessary  to  proceed  further,  and  make  two  other  pre- 
liminary experiments  previous  to  coating  the  plates 
with  collodion. 

One  of  these  experiments  is  intended  to  ascertain 
whether  the  collodion  is  bromo-iodized  to  a  proper  ex- 
tent for  the  purpose.  To  make  the  test,  coat  a  small 
plate  with  the  collodion  in  question,  and  after  allowing 
the  film  to  set,  immerse  it  in  the  silver  bath.  If  the 
film  soon  assumes  a  cream  color  in  the  solution,  the 
collodion  indicates  a  proper  condition  for  working  well ; 


THE  TANNIN   PROCESS. 


33 


whereas,  if  the  film  remains  bluish  after  several  minutes' 
immersion,  this  is  an  indication  either  that  there  is  too 
small  a  quantity  of  pyroxyline,  or  that  the  bromo-iodides 
are  not  in  proper  proportion  in  reference  to  the  different 
salts  used,  or  in  too  small  a  quantity  combinedly.  If 
the  collodion  has  the  requisite  degree  of  consistence,  as 
indicated  by  the  first  test-trials,  the  defect  is  attribu- 
table to  the  salts,  whose  quantity  and  relative  propor- 
tions have  to  be  so  modified  until  the  desired  effect  is 
attained.  The  blueness  of  the  film  just  alluded  to, 
however,  more  generally  is  owing  to  a  want  of  more 
pyroxyline,  and  hence  of  more  of  the  bromo-iodizers,  as 
a  consequence.  Add,  in  such  a  condition,  both  more 
cotton  and  more  of  the  salts.  Bear  in  mind,  too,  that 
the  ammonia  salts  have  a  tendency  to  make  the  collodion 
more  thin,  while  the  cadmium  salts  have  an  opposite 
tendency,  and  render  it  more  consistent  and  glutinous. 
The  other  experiment  is  now  to  see  whether  the  col- 
lodion produces  those  acicular  specks  or  pinholes,  which 
are  the  very  bane  of  a  good  photographer.  Consequently 
coat  with  collodion,  sensitize  the  film,  expose,  develop, 
fix,  and  wash.  The  film  now  can  be  examined  ;  if  the 
pinholes  are  absent  you  are  a  lucky  man  ;  if  not,  you 
must  proceed  a  few  steps  further.  The  first  thing  you 
have  now  to  do  is  to  filter  the  collodion.  Place  rather 
loosely  in  the  neck  of  the  funnel  a  small  piece  of  clean 
and  dry  cotton-wool,  and  pour  the  collodion  into  the 
funnel,  which  is  supposed  to  be  supported  on  a  retort 
stand,  or  otherwise  in  such  a  way  as  to  enable  you  to 
collect  the  collodion  in  a  bottle  beneath,  as  it  filters 
through.  A  piece  of  glass  is  placed  over  the  funnel  to 
prevent  the  evaporation  of  the  ether.  The  first  portions 
of  the  filtrate,  which  may  contain  fibres  of  the  cotton, 
are  poured  back  into  the  collodion  on  the  filter,  a  fresh, 
clean  bottle  is  placed  beneath  to  receive  the  clear  col- 


34  DRY  PLATE  PHOTOGRAPHY  ;  OR, 

lodion,  and  the  bottle  previously  used  is  thoroughly 
rinsed  out  with  ether,  which  is  added  to  the  collodion 
in  the  funnel  to  make  up  for  that  portion  which  is  lost 
by  evaporation.  This  mode  of  filtering  is  somewhat  de- 
fective, because  of  the  loss  of  ether  by  evaporation,  and 
of  the  consequent  coagulation  of  the  collodion  itself 
around  the  cotton  in  the  neck  of  the  filter,  whereby  the 
filtration  is  frequently  impeded  or  entirely  stopped. 
Collodion  filters  can  be  purchased,  which  obviate  this 
defect  altogether.  The  collodion  is  completely  isolated 
from  the  air,  excepting  that  portion  which  is  contained 
in  the  filter  and  receiver  ;  and  an  arrangement  is  made 
in  the  neck  of  the  filter,  by  which  the  collodion  can  pass 
downward  through  the  cotton,  while  an  equivalent 
quantity  of  air  from  the  receiver  beneath  passes  up- 
ward to  take  its  place.  Such  filters  are  almost  indis- 
pensable in  every  photographic  establishment,  and  may 
be  relied  upon  to  perform  the  operation  for  which  they 
are  constructed. 

It  is  advisable  to  filter  the  collodion  at  least  twice  ; 
by  this  means  it  will  become  completely  deprived  of 
undissolved  particles  both  of  pyroxyline  and  the  bromo- 
iodizing  salts. 

Another  experiment  is  now  made,  as  before,  to  see 
whether  the  pinholes  still  exist  or  not ;  if  they  are 
still  present,  filter  the  silver  solution,  and  wash  out  the 
bath  very  carefully.  Return  the  filtered  solution,  and 
try  the  collodion  once  more.  If  the  acicular  plagues 
are  still  present,  you  must  add  a  few  ounces  of  rain  or 
distilled  water  to  the  silver  bath,  filter  once  more,  and 
then  finally  add  a  quantity  of  the  crystals  of  the  nitrate 
of  silver,  proportionate  to  the  number  of  ounces  of  water 
first  poured  into  the  solution,  to  produce  a  precipitate. 
After  all  these  operations  have  been  performed,  the 
collodion,  as  a  general  rule,  will  be  found  to  work  well, 


THE   TANNIN    PROCESS.  35 

and  you  may  now  proceed  to  the  next  operation,  which 
consists  in  sensitizing  the  collodion  film.  The  remain- 
ing part  of  this  chapter  you  may  skip  over,  and  read  at 
your  leisure. 

The  late  Mr.  Glover  made  several  excellent  experi- 
ments in  reference  to  the  manufacture  of  pyroxyline  for 
the  tannin  process.  For  those  who  may  feel  inclined 
to  prepare  this  article  themselves  we  insert  Glover's 
formulas,  as  also  those  of  Major  Russell. 

The  clean  and  pure  cotton  of  commerce,  either 
Egyptian  or  American,  the  former  being  preferred,  is 
first  purified  of  a  certain  quantity  of  gummy  substance 
which  it  contains,  by  the  following  expedient  : 

FORMULA    FOR   PURIFYING   COTTON    FOR   THE    MANUFACTURE    OF 
PYROXYLINE. 

Carded  cotton       .  .         .4  ounces. 

Potash      .    "     .         .         .         ,          2  ounces. 
Rain-water  .         .         .         .         .10  pints. 

The  water  is  firs-braised  to  the  boiling  temperature 
in  a  glazed  porcelain  or  glass  vessel ;  the  potash  is 
then  dissolved,  and  the  cotton  introduced.  The  mixture 
is  kept  boiling  for  a  couple  of  hours,  a  sufficient  quan- 
tity of  water  being  added  from  time  to  time  to  make 
up  for  the  loss  by  evaporation  ;  and  the  whole  is  fre- 
quently stirred  with  a  glass  spatula.  After  this  opera- 
tion of  boiling,  the  cotton  is  taken  out  and  thrown  into 
a  running  stream  of  water,  or  washed  in  several 
changes  of  water,  in  order  to  remove  every  trace  of 
the  alkali.  The  absence  of  all  alkaline  reaction  is 
shown  by  red  litmus  paper,  which  remains  unchanged 
in  the  wash  water.  If  this  paper  turns  slightly  blue,  it 
is  a  sure  indication  that  the  alkali  is  still  present.  The 
cotton,  being  thus  perfectly  freed  from  the  alkali,  is 
dried  perfectly  by  the  heat  of  the  sun,  or  by  artificial 


36  DRY  PLATE  PHOTOGRAPHY  ;   OR, 

heat.     This  is  Hardwich's  method  of  preparing  cotton 
for  the  preparation  of  pyroxyline. 

GLOVER'S  FORMULA  FOR  PREPARING  PYROXYLINE. 
Sulphuric  r.cid  (sp.  gr.  1.845)     .     10  ounces. 
Nitric  acid  (sp.  gr.  1.37)         .          5  ounces. 
Water  .         .        .        .        .     2  drachms. 

Cotton    (prepared  by  the  above 

formula)     .         .         .         .         300  grains. 
Temperature        ....  145°  Fahr. 
Time        .        .        .        .        .         10  minutes. 

A  water  bath  is  prepared,  in  which  the  water  is 
raised  to  the  temperature  of  145°  and  maintained  at 
this  heat.     The  acids  and  water  are  mixed  together  in 
a  separate  vessel,  which  is  placed  in  the  water  bath. 
As  soon  as  the  temperature  of  the  mixed  acids  has 
lowered  to  that  of  this  bath,  that  is,  of  145°,  the  cotton, 
which  has  previously  been  divided  up  into  light  tufts, 
is  introduced  quickly,  one  by  one,  into  the  acids,  and 
thoroughly  immersed.     As  soon  as^iey  are  all  in  the 
liquid,  and  not  matted  together,  the  vessel  is  covered 
up,  and  allowed  to  stand  at  the  given  temperature  for 
ten  minutes.     At  the  expiration  of  this  time  the  cotton 
is  taken  out  by  means  of  two  glass  rods  or  spatulas, 
and  thrown  into  a  pail  of  water;  by  this  immersion  the 
largest  proportion  of  the  acids  in  the  altered  cotton  is 
removed.     The  remaining  parts  of  the  acids  is  removed 
by  working  around  the  cotton  in  a  running  stream  of 
water,  or  in  several  changes  of  fresh  water.     To  the 
last  change  of  water  about  ten  grains  of  bicarbonate  of 
soda  are  added.     Every  trace  of  acidity  must  be  re- 
moved ;  and  the  entire  absence  of  acidity  is  indicated 
by  means  of  blue  litmus  paper,  which  remains  blue  in 
the  wash-water  ;  the  paper,  however,  turns  red,  more 
or  less  rapidly,  according  to  the  quantity  of  acid  still 


THE   TANNIN   PROCESS.  of 

present.  The  cotton  by  this  process  has  become  altered, 
has  combined  with  some  of  the  elements  of  nitric  acid, 
and  has  increased  in  weight ;  it  is  now  denominated 
pyroxyline.  This  pyroxyline  is  taken  out  of  the  water, 
separated  into  small  tufts,  and  placed  on  a  large  sheet 
of  paper  to  dry  in  the  sun.  It  is  preferable  to  dry 
pyroxyline  in  the  sun  rather  than  by  artificial  heat,  in 
order  to  avoid  explosions,  which  have  been  very  dis- 
astrous even  in  experienced  hands.  When  thoroughly 
dry,  the  pyroxyline  is  divided  up  into  ounces  and  care- 
fully packed  in  card-board  or  tin  boxes  for  future  use. 

Collodion,  which  produces  a  dense  and  horny  film,  is 
well  adapted  for  the  tannin  process  ;  but  such  a  film  is 
not  so  sensitive  as  &  porous  film.  Both  these  conditions 
in  the  film  depend  in  a  great  measure  upon  the  nature 
of  the  pyroxyline,  which  is  modified  by  the  temperature 
of  the  acids  in  which  the  cotton  is  immersed.  Thus  a 
high  temperature  produces  a  porous  film  ;  and  the  same 
effect  can  be  produced  by  a  larger  proportion  of  water 
in  the  acids,  a  longer  immersion  and  a  lower  tempera- 
ture. Collodion  prepared  from  cotton  prepared  accord- 
ing to  Glover's  formula  is  very  sensitive,  and  flows 
easily  over  the  plate.  For  this  collodion  two  grains  of 
iodide  of  ammonium  and  six  grains  of  the  cadmium  salts 
to  the  ounce  will  work  well. 

The  formula  which  Major  Russell  uses  for  his  collo- 
dion in  the  tannin  process  is  the  following  : 

THE  TANXING  PROCESS. 

Alcohol  (.805  sp.  gr.)  .         .  .10  ounces. 

Ether 10  ounces. 

Pyroxyline 120  grains. 

Iodide  of  ammonium         .         .          20  grains. 

Iodide  of  cadmium       .         .   .  .     6t|  grains. 
Bromide  of  cadmium         .         .         52|  grains. 
2 


38  DRY  PLATE  PHOTOGRAPHY;    OR, 

There  seems  to  have  been  lately  a  desire  to  set  aside 
the  iodides  altogether  in  dry  plates,  and  to  depend 
solely  on  the  bromide  of  silver.  Mr.  Sayce's  latest 
experiments,  which  appear  to  have  been  crowned  with 
decidedly  successful  results,  have  been  founded  entirely 
on  bromide  of  silver  diffused  through  the  collodion, 
which  naturally  has  to  be  kept  in  a  dark  or  non-actinic 
place.  My  own  experiments,  in  trying  to  reproduce 
these  results,  have  not  been  so  successful ;  a  picture, 
it  is  true,  was  easily  obtained,  but  exceedingly  faint, 
and  incapable  of  the  requisite  intensification.  The  de- 
fect alluded  to  is  manifest  also,  to  some  degree,  in  the 
bromide  process,  as  marked  out  by  Major  Russell  him- 
self. He  remarks  on  this  subject  as  follows : 

"  Bromo-iodized  collodion  will  produce  good  results, 
but  simply  bromized  collodion  is  strongly  recommended 
as  being  in  most  cases  preferable ;  the  latter  is  about 
twice  as  sensitive  as  the  former ;  and  seems,  so  far  as 
it  has  been  tried,  to  have  no  tendency  while  in  the  excit- 
ing bath  to  form  needle-shaped  crystals,  which* are  so 
common  an  annoyance  when  the  collodion  contains 
iodide.  Above  all,  the  bromized  collodion  will  produce 
a  better  negative  when  the  subject  presents  great  con- 
trast, such  as  sky  and  dark  objects,  as  it  will  bear 
over-action  of  light  better,  and  shows  no  tendency  to 
produce  blurring  along  the  edges  of  the  strongly  lighted 
parts  of  the  subject. 

"Bromized  collodion  seems  to  be  particularly  suitable 
for  use  with  tannin.  In  a  great  number  of  trials  with 
different  kinds  of  collodion,  and  various  modes  of 
treatment,  the  iodide  and  bromide  in  no  one  instance 
approached  the  bromide  in  sensitiveness,  even  when 
the  latter  was  used  in  a  much  less  sensitive  collodion, 
or  in  quality  of  negative  with  a  landscape  subject  when 
both  were  exposed  long  enough  for  the  darkest  parts. 


THE   TANNIN   PROCESS.  39 

"  Two  precautions  are  necessary  when  bromide  alone 
is  used  :  First,  not  to  use  a  very  slow-setting  collodion  ; 
probably  almost  any  sample  intended  for  the  wet  pro- 
cess will  answer.  Second,  to  excite  in  a  strong  bath, 
and  keep  the  plate  in  long  enough." 

He  further  on  remarks,  that  collodion  made  with 
Glover's  pyroxyline  does  not  set  quickly  enough,  but 
may  be  made  to  work  correctly  in  this  respect  by  using 
cotton  immersed  in  the  mixed  acids  at  a  temperature  of 
125°  Fahr.  and  keeping  it  there  for  20  minutes.  The 
remaining  treatment  is  the  same  as  already  described. 
The  gain  in  weight  by  such  a  proceeding  is  about  50 
per  cent. 

The  bromized  collodion  recommended  by  Major 
Russell  is  composed  as  follows  : 

"  Pyroxyline    .         .         .         .  .5  grains. 
Bromide  of  cadmium          .         .         8  grains. 

Alcohol  (.805  sp.  gr.)   .         .  .4  drachms. 

Ether 4  drachms. 

"  Put  the  whole  in  a  tall,  narrow  bottle,  shake  up  until 
the  solution  of  the  pyroxyline  and  the  bromide  is  com- 
plete ;  then  allow  to  settle  clear  and  decant.  If  the 
alcohol  is  weaker,  or  if  the  pyroxyline  is  of  a  kind 
likely  to  give  too  little  setting  power,  a  larger  propor- 
tion of  ether  should  be  used. 

"  The  addition  of  a  few  drops  of  astrong  alcholic  solu- 
tion of  bromine*  to  an  ounce  of  the  collodion  seems  to 
be  an  improvement ;  but  bromine  can  only  be  used  with 
a  quick-setting  collodion,  as  it  tends  still  more  than 
bromide  to  retard  the  setting.  The  yellow  color  given 
by  the  bromine  will  probably  soon  disappear,  but  the 
collodion  will  retain  an  acid  reaction." 

*  Take  equal  parts  by  volume  of  bromine  and  alcohol  to  make  the 
alcoholic  solution  recommended. 


40       .  DRY  PLATE  PHOTOGRAPHY. 

Although  bromized  collodion  may  be  more  sensitive 
than  bromo-iodized  collodion,  it  is  much  more  difficult 
to  obtain  intensity  by  the  former  than  by  the  latter  ; 
besides  this,  it  requires  a  longer  time  to  reduce  the 
bromides  in  the  collodion  into  bromide  of  silver,  than 
to  produce  the  same  result  from  the  iodides  or  bromo- 
iodides.  The  same  want  of  intensity  appears  to  be  the 
drawback  in  Sayce's  new  process  of  preparing  dry 
plates  without  the  silver  bath  ;  the  image  is  easily 
brought  out,  but  in  our  hands,  hitherto,  it  lacks  vigor. 
This  is  probably  owing  to  the  fact  that  bromide  of 
silver  alone  is  employed  in  the  production  of  the  image. 

The  reader,  therefore,  is  advised  at  present  to  adhere 
to  the  collodion  formulas  given  at  the  beginning  of  the 
chapter,  or  to  make  use  of  the  collodions  prepared  by 
our  first-class  photographic  establishments. 


CHAPTER     III. 

SENSITIZING   THE   PLATES. 

To  sensitize  the  plates  for  the  dry  process  is  a  com- 
pound operation  ;  and,  by  reason  of  much  formality,  has 
deterred  many  operators  from  having  any  thing  to  do 
with  the  process.  Three  solutions  are  required  in  the 
first  place — namely,  the  silver  bath,  the  tannin  solution, 
and  a  solution  of  any  of  the  bromides. 

SILVER    SOLUTION    OR   BATH. 

The  best  results  are  always  obtained  with  a  strong 
acid  new  bath  ;  it  is  true,  .that  any  silver  solution  that 
answers  for  the  wet  process  will  be  suitable  for  the 
dry  process,  but  the  best  conditions  can  not  always  be 
thus  obtained.  If  convenient  to  have  a  separate  bath 
for  the  dry  process,  prepare  it  in  the  following  manner  : 

Pure  crystallized  nitrate  of  silver  .  4  ounces. 
Distilled  or  rain  water  .  .  32  ounces. 
Acetic  acid 1  drachm. 

Divide  the  bath  into  two  halves  and  saturate  one 
of  them  with  well-washed  iodide*  of  silver.  This  is 
effected  by  mixing  with  this  half  an  excess  of  iodide  of 
silver,  and  shaking  the  mixture  thoroughly  ;  the  solu- 
tion is  then  filtered  and  mixed  with  the  other  half  for 
use.  A  stronger  solution  of  silver  can  be  kept  on  hand 

*  Add  to  a  solution  of  twenty  grains  of  iodide  of  potassium  nitrate 
of  silver  in  solution  as  long  as  there  is  any  precipitate ;  the  pre- 
cipitate, when  settled,  is  separated  from  the  nitrate  of  potassa,  and 
washed  in  several  changes  of  water. 


42  DRY  PLATE  PHOTOGRAPHY;    OR, 

ready  for  strengthening  the  bath  when  required.  More 
acetic  acid  can  be  used  with  advantage  in  the  dry  pro- 
cess than  in  the  wet  process  ;  but  it  must  be  remem- 
bered that  it  tends  to  diminish  the  sensitiveness  in 
some  degree,  at  least  such  is  the  received  opinion.  For 
our  own  part  we  do  not  think  it  has  much  influence  in 
this  respect,  because  all  the  free  acid  is  entirely  re- 
moved by  the  subsequent  operations,  arid  the  sensitive- 
ness depends  upon  the  tannin  solution  with  which  the 
film  is  coated.  Keep  the  bath  in  a  place  free  from  dust; 
that  is,  cover  it  up  when  not  in  use  ;  and  when  it  be- 
comes saturated  with  alcohol  and  ether,  boil  it  until 
these  ethereal  solutions  have  evaporated,  and  then  filter 
the  bath  for  use  again. 

TANNIN    SOLUTION. 

There  is,  no  doubt,  a  difference  in  the  various  speci- 
mens of  tannin  in  commerce,  but  as  yet  we  are  not  in 
condition  to  say  which  is  the  best ;  this  much,  however, 
is  known,  every  variety  of  tannin  may  be  used,  and  with 
almost  equal  advantage,  after  it  has  been  kept  in  solu- 
tion some  time  and  filtered  ;  for  by  this  means  the 
impurities  have  time  to  settle,  and  by  filtration  are 
removed. 

Commercial  tannin    ...       4  drachms. 

Distilled  or  rain  water  .         .         16  ounces. 

Loaf  Sugar        ....       4  drachrns. 

Shake  the  mixture  well  until  the  solution  is  complete* 
and  put  it  aside  for  a  day  or  two.  After  this  time  it 
may  be  filtered  through  moist  filtering  paper.  The  fil- 
tration can  be  repeated  several  times.  Finally,  add 
half  an  ounce  of  alcohol  to  the  solution.  By  use  this 
solution  receives  particles  of  dust,  which  must  be 
removed  by  filtration  every  time  it  is  used  for  the 
preparation  of  a  fresh  quantity  of  dry  plates.  A  larger 


THE  TANNIN  PROCESS. 


43 


or  a  smaller  proportion  of  tarmin  than  that  indicated 
in  the  formula  may  be  employed  without  making  much 
difference  perceptible  in  the  results,  as  long  as  the 
plates  are  immersed  sufficiently  long  in  the  solution  to 
produce  the  proper  degree  of  sensitiveness.  If  the  al- 
cohol be  omitted  in  the  tannin  solution,  the  latter  is  apt 
to  grow  mouldy  on  the  surface  ;  but  after  filtration  we 
have  not  observed  that  such  a  solution  has  been  in  any 
way  impaired  in  its  sensitizing  properties.  The  alcohol 
therefore  seems  to  be  added  simply  to  prevent  a  film 
of  mouldiness,  which  necessitates  filtration. 

BROMIDE  SOLUTION. 

Bromide  of  cadmium     .         .         .1  drachm. 
Distilled  or  rain  water       .         .         6  ounces. 

We  are  now  ready  for  the  sensitizing  operation. 
Take  from  the  rack  a  plate  that  has  been  already 
coated  with  albumen,  or  whose  edges  have  been  var- 
nished with  albumen,  remove  any  adhering  particles  of 
dust  from  its  surface,  by  means  of  a  broad,  flat  camel's 
hair  pencil,  and  then,  after  heating  the  plate  to  drive 
away  the  moisture  and  allowing  it  to  cool,  coat  this 
surface  with  collodion  in  the  usual  manner  ;  after  the 
collodion  has  set  sufficiently,  the  plate  is  immersed  in 
the  silver  bath,  where  it  is  allowed  to  remain  until  all 
apparent  greasiness  of  surface  has  been  removed,  and 
the  proper  reductions  have  been  effectuated.  The  film 
jiiust  now  have  a  uniform,  cream-like  appearance  ;  if 
it  is  or  remains  blue  or  bluish,  the  collodion  is  in  fault, 
or  the  time  of  immersion  has  been  too  short.  Keep 
the  plate  in  the  solution  until  the  desired  condition  has 
been  attained. 

It  appears  from  the  recent  experiments  of  Poitevin 
on  the  sensitizing  properties  of  tannin,  that  this  opera- 
tion of  producing  either  the  iodide  or  bromide  of  silver 


44  DRY  PLATE  PHOTOGRAPHY  J  OR, 

in  the  collodion  film  maybe  performed  in  the  light  of  day  ; 
but  until  we  are  quite  certain  as  to  the  practicability  of 
this  plan,  we  recommend  that  the  collodion  plates  be 
immersed  in  the  silver  solution  in  the  dark  or  non-actinic 
room. 

Supposing  the  color  of  the  collodion  film  is  cream-like 
and  uniform,  that  is,  free  from  all  oiliness,  raise  it  from 
the  silver  bath,  allow  it  to  drain,  and  then  place  it  in  a 
large  flat  dish  of  rain  or  distilled  water,  with  the  film- 
side  upward. 

In  the  mean  while  proceed  as  with  the  first  plate,  and 
coat  a  second  plate  with  collodion  ;  allow  the  film  to 
set,  and  immerse  the  plate  in  the  silver  solution.  While 
the  reduction  is  thus  going  on  in  the  silver  bath,  return 
to  the  first  plate,  take  it  out  of  the  dish  of  rain-water, 
and  wash  the  film  under  the  tap,  in  the  same  manner  as 
you  would  a  negative. 

This  washing  aims  to  remove  all  the  free  nitrate  of 
silver  and  the  other  soluble  nitrates,  such  as  nitrate  of 
cadmium  and  of  ammonia,  from  the  film.  By  washing 
alone  this  aim  can  not  be  thoroughly  effected,  at  least 
it  is  so  supposed,  and  consequently  the  next  operation 
is  intended  to  convert  any  trace  of  remaining  nitrate  of 
silver  into  bromide  of  silver.  For  thip  purpose  flow 
over  the  film  a  sufficient  quantity  of  the  bromide  solu- 
tion two  or  three  times,  and  return  the  residue  into  the 
stock  bottle  for  future  use. 

The  film  is  again  washed  under  the  tap  to  remove  all 
traces  of  the  bromide  solution  or  the  resulting  nitrate 
of  cadmium. 

The  final  operation  consists  now  in  coating  the  film 
with  the  solution  of  tannin.  This  can  be  done  either  by 
pouring  the  solution  two  or  three  times  backward  and 
forward  over  the  film,  and  allowing  the  residue  to  drain 
into  the  stock  bottle,  or  by  immersing  the  plate  on  a 


THE   TANNIN    PROCESS.  45 

dipper  in  a  vertical  bath  containing  the  tannin  solution. 
The  latter  plan  is  more  convenient ;  and  while  the  plate 
is  in  the  tannin  bath,  you  can  examine  the  plate  in  the 
silver  solution  •  if  the  latter  be  ready,  move  the  tannin 
plate  up  and  down  in  the  solution  for  about  a  rninute, 
then  raise  it  out,  and,  after  it  has  sufficiently  drained, 
place  it  in  the  drying  chamber,  and  proceed  with  each 
successive  plate  in  the  same  manner. 

We  find  it  to  be    a  disadvantage   to  prolong   the 
operations  of  washing  in  any  of  the  stages  too  long  ; 
this  is  owing,  probably,  to  the  fact  that  the  surface 
bromide  or  iodide  of  silver  is  removed  by  the  mechanical 
friction  of  the  water  ;  let,  therefore,  the  operation  of 
washing  be  gentle.    But  we  have,  furthermore,  observed 
that  the  results  are  still  worse  if  the  plate  is  made  to  pass 
through  several  changes  of  water  in  separate  dipping 
baths,  and  thus  allowed  to  remain  for  more  than  half  an 
hour  in  the  water.    The  cause  may  be  the  same  in  both 
cases — the  mechanical  removal  of  the  fine  pulverulent 
bromide  or  iodide  of  silver  from  the  surface  of  the  collo- 
dion, by  disintegrating  them  from  their  attachment  to  the 
matrix.     We  prefer  washing  the  plates  at  the  tap,  as  we 
have  just  described,  to  immersing  them  in  a  series  of 
baths,  because  there  is  always  sufficient  time  to  perform 
the  whole  operation  before  another  plate  is  ready,  and 
because  the  act  is  simple,  effective,  and  free  from  all 
further  outlay.    The  drying  rack,  which  has  been  already 
described,  may  be  used  here  ;  but  in  this  case  it  must 
have  been  varnished  with  two  or  three  coats  of  good 
varnish,  and  must  be  washed  carefully,  and  dried  every 
time  it  has  to  be  used  ;  otherwise,  the  parts  upon  which 
the  plates  rest,  having  collected  impurities  in  the  form 
of  dust,  etc.,  will  be  liable  to  contaminate  the  plates 
that  are  draining  by  capillary  attraction.     A  simple  plan 
of  draining  and  drying  the  plates  is  to  rear  each  upon 


46  DRY  PLATE  PHOTOGRAPHY  ;  OR, 

one  corner,  standing  on  a  piece  of  clean  blotting  paper, 
and  to  renew  the  paper  as  soon  as  the  excess  of  fluid 
has  drained  off. 

Drying  chambers  may  be  constructed  for  the  purpose 
in  question,  by  means  of  which  the  plates  are  thoroughly 
prevented  from  coming  in  contact  with  any  thing  that 
might  in  any  way  tend  to  soil  them  ;  while,  at  the 
same  time,  all  access  of  light  is  shut  out.  The  author 
has  such  a  chamber,  which  essentially  is  an  oblong  box, 
opening  on  either  side,  but  closed  in  at  the  two  ends, 
and  at  the  top  and  bottom.  On  the  bottom  board  at 
either  end  in  the  middle  is  screwed  a  small  cubical 
block  one  inch  high  ;  and  stretching  from  each  of  these 
and  screwed  firmly  to  them  is  a  piece  of  wood  half  an 
inch  thick  and  one  inch  wide.  Along  the  middle  of  this 
holes  are  cut,  to  receive  pieces  of  glass  tubing,  each  one 
inch  in  length  ;  these  pieces  of  glass  tube  are  easily 
cut  from  a  glass  rod,  by  filing  a  circle  round  the  tube 
at  the  distance  of  one  inch  each  from  the  end  ;  each 
piece  then  may  be  broken  off  with  facility.  The  edges 
of  the  little  tubes  are  either  filed  or  ground  on  a  grind- 
stone. They  are  finally  inserted  in  the  holes  on  the 
longitudinal  cross-bar,  and  cemented  there  by  means  of 
shell-lac,  and  in  such  a  way  that  there  is  an  equal  por- 
tion of  the  tube  above  and  below  it.  The  holes  in 
which  the  tube  are  fixed  are  one  inch  and  one  quarter 
apart. 

The  next  part  of  the  construction  is  to  prepare  a 
number  of  small  blocks  of  wood,  cubical  in  shape  and 
one  inch  along  each  side.  The  number  of  these  will 
correspond  with  the  number  of  holes  in  which  the  glass 
tubes  are  fixed. 

Apertures  of  the  same  size  as  those  already  men- 
tioned are  bored  in  the  centre  of  one  surface  and  pro- 
ceed to  within  an  eighth  of  an  inch  or  so  from  the 


THE  TANNIN  PROCESS. 

opposite  surface.  These  apertures  are  for  the  reception 
of  similar  pieces  of  tubing  to  those  above  mentioned. 
These  pieces  are  also  fixed  in  their  places  by  means  of 
melted  shell-lac. 

Now  cut  off  pieces  of  brass  wire,  one-eighth  of  an 
inch  in  diameter,  or  even  thicker,  and  three  inches  in 
length.  Flatten  out  either  end  of  each  wire  on  the 
same  side,  and  drill  holes  through  the  flattened  parts 
for  the  passage  of  small  screws.  A  piece  of  wire  is  now 
screwed  firmly  to  each  block,  arid  to  that  surface 
through  which  the  hole  does  not  penetrate  but  nearly 
reaches. 

On  the  upper  part  of  the  box  and  in  the  inside,  and 
along  a  line  running  Jongitudinally  and  parallel  with 
the  middle,  a  piece  of  inch  stuff  is  screwed.  This  piece 
naturally  projects  downward  into  the  box  to  the  amount 
of  one  inch.  To  the  under  surface  of  this  projection 
the  opposite  end  of  each  wire  just  mentioned  is  screwed, 
and  so  that  the  opening  of  the  glass  tube  in  the  block 
of  wood  at  the  other  end  looks  downward  and  exactly 
overhead  and  corresponding  to  a  glass  tube  beneath. 
The  two  glass  tubes,  the  one  above  and  the  other 
below,  are  thus  situated  in  the  same  perpendicular 
straight  line.  The  distance  between  the  nearest  ex- 
tremities of  these  two  tubes  must  be  about  half  an  inch 
or  three-quarters  of  an  inch  less  than  the  length  of  the 
diagonal  of  the  glass  plates  you  use  for  the  dry  process. 
Owing  to  the  flexibility  of  the  wire,  each  block  of  wood 
admits  of  being  pressed  upward  to  the  amount  of  one 
inch  ;  and,  when  so  pressed  upward,  the  upper  corner 
of  a  plate  to  be  drained  and  dried  is  inserted  into  the 
open  cavity  of  the  little  tube  ;  the  plate  is  then  lowered 
until  the  opposite  diagonal  corner  of  the  plate  rests 
upon  the  open  cavity  of  the  tube  below.  The  collodion 
film  is  always  turned  away  from  the  hand  and  placed 


48  DRY  PLATE  PHOTOGRAPHY  J  OR, 

parallel  to  the  end  of  the  box  which  it  faces.  From  the 
nature  of  the  construction  it  is  evident  that  the  plate 
when  so  placed  will  be  kept  in  its  position  by  the  elastic 
pressure  of  the  wire  above  ;  also  that  the  drainings 
from  each  glass  will  pass  down  each  little  tube,  and 
may  be  caught  in  a  proper  receptacle  below,  or  on 
blotting  paper  ;  and,  from  the  fact  that  the  plate  comes 
in  contact  only  with  these  two  pieces  of  tubing  in  four 
small  points,  it  seems  improbable  that  stains  can  thus 
be  produced.  While  the  plates  are  draining  and  dry- 
ing, the  two  side  doors  are  left  open,  but  the  upper  side 
or  lid  prevents  the  deposition  of  dust  from  above.  In 
this  position  the  prepared  plates  are  left  in  the  dark 
room  over  night  or  an  equivalent  portion  of  time,  and 
then  the  side  lids  are  adjusted  in  their  places.  The 
plates  may  thus  be  preserved  until  they  are  wanted. 

It  is  immaterial  whether  the  plates  are  allowed  to  dry 
spontaneously  in  a  drying  chamber  as  just  described,  or 
are  dried  by  artificial  heat,  as  long  as  the  operation  is 
uniform  ;  but  if  there  is  any  irregularity  in  the  temper- 
ature on  different  parts  of  the  same  plates,  it  will  be 
manifested  by  a  corresponding  irregularity  in  the  collo- 
dion film  when  you  come  to  the  development  of  the 
image. 

Plates  are  best  dried  in  a  steam-tight  cupboard  made 
of  tin  plate,  and  furnished  with  ventilating  tubes  to 
allow  air  to  pass  in  arid  steam  out,  while  at  the  same 
time  all  light  must  be  carefully  excluded.  The  sides, 
top,  and  bottom  of  such  a  cupboard  are  hollow  cavities, 
into  which  steam  is  admitted  from  a  small  steam  kettle 
situated  close  by,  in  which  the  water  is  kept  briskly 
boiling  by  means  of  a  lamp  or  small  charcoal  fire.  The 
steam  as  it  condenses  is  caught  below ;  and  the  hot 
water  thus  procured  is  poured  back  again  into  the 
^team-boiler  from  \ii&e  to  time;  as  it  accumulates. 


THE  TANNIN  PROCESS.  49 

a  drying  chamber  must  also  be  furnished  with  pieces  of 
glass  tubes  to  hold  the  plates,  or  some  equivalent 
arrangement,  whereby  capillary  attraction  can  be  pre- 
vented. Plates  may  thus  be  dried  in  five  minutes  or 
less,  and  are  thus  immediately  ready  for  packing  away 
or  for  use. 

Upon  the  whole,  we  prefer  this  plan  of  drying  plates 
by  artificial  heat ;  for  the  plates  are  dried  not  only 
quickly,  but  more  thoroughly  and  uniformly  than  they 
can  be  spontaneously. 

Dry  plates  are  packed  differently  for  transportation 
and  for  present  use.  In  the  latter  case  a  proper  quan- 
tity are  placed  at  once  in  the  changing  box,  to  be  de- 
scribed hereafter,  or  in  small  boxes  furnished  with 
grooves  on  two  opposite  sides  for  their  reception, 
similar  to  the  boxes  prepared  for  melainotype  plates. 
These  boxes  must  be  quite  impervious  to  light.  The 
plates  are  always  packed  with  the  film  in  a  fixed  and 
given  direction,  in  order  to  avoid  mistakes  on  exposure ; 
otherwise  it  might  easily  happen,  that  the  bare  surface 
of  the  glass  might  be  exposed  instead  of  the  collodion 
film. 

For  transportation  or  manufacturing  purposes,  dry 
plates  are  packed  in  a  different  manner.  Rectangular 
pieces  of  thick  paper  are  cut  out,  the  size  of  the  glass 
plate.  The  inside  of  these  pieces  are  also  cut  away, 
leaving  thus  a  sort  of  paper  frame  of  about  a  quarter  of 
an  inch  thick  in  width  all  round.  Such  a  paper  frame 
is  placed  upon  the  collodion  side  of  the  glass  ;  over  this 
comes  another  prepared  plate,  collodion  side  upward  ; 
then  another  rectangular  piece  of  paper ;  and  so  on 
until  a  dozen  or  a  score  are  thus  placed  completely 
together.  An  unprepared  glass  plate,  or  a  prepared 
plate  turned  collodion  si^e  downward,  is  placed  last. 
This  appendage  of  plates  is  ROW  folded  up  in  several 


50  DRY  PLATE  PHOTOGRAPHY  ;   OR, 

coverings  of  orange-colored  paper,  and  finally  stored 
away  in  small  boxes  made  on  purpose  for  their  recep- 
tion. 

In  all  the  operations  previously  described,  from  the 
moment  that  the  plates  are  sensitized,  it  is  absolutely 
necessary  to  exclude  actinic  light,  even  the  light  of  a 
lamp  or  candle  will  be  injurious.  The  author  manipu- 
lates in  comparative  darkness.  Without  this  caution 
the  plates  are  liable  to  fogging,  which  is  frequently  at- 
tributed to  the  collodion,  the  silver  bath,  or  developer. 

Some  authors  recommend  the  film  to  be  washed  after 
it  has  been  finally  coated  with  the  tannin  solution.  AVe 
do  not  think  this  operation  necessary  ;  in  fact,  it  entails 
a  loss  of  time,  and  it  has  been  our  opinion  that  the  pic- 
ture was  less  intense  in  those  cases  where  the  film  had 
been  so  treated. 

While  performing  the  different  manipulations  de- 
scribed, the  hands  must  be  kept  rigorously  clean.  To 
avoid  stains  that  might  arise  from  impurities  from  the 
hands,  while  coming  in  contact  with  different  fluids, 
such  as  nitrate  of  silver,  bromide  of  potassium,  and 
tannin,  the  pneumatic  holder  will  be  found  very  con- 
venient. But  the  same  caution  must  be  applied  to  keep 
this  clean,  though  there  is  not  the  same  amount  of 
danger  of  stains  to  be  derived  from  the  holder  as  from 
the  hands.  When  the  holder  is  not  used,  it  is  advisable 
to  rinse  the  hands  thoroughly  after  the  preparation  of 
each  plate  ;  otherwise  the  last  fluid  used  (tannin)  may 
come  in  contact  directly  with  nitrate  of  silver  on  the 
film,  and  this  will  certainly  produce  a  stain. 

Furthermore,  if  the  plates  are  dried  spontaneously  by 
rearing  them  on  one  corner  on  pieces  of  bibulous  paper, 
it  is  necessary  to  throw  away  every  piece  of  paper  that 
has  been  already  used.  See,  too,  that  the  shelves  on 
which  the  plates  are  reared  up,  are  well  cleaned  (even 


THE  TANNIN  PROCESS.  51 

washed  and  dried)  before  you  begin  to  prepare  your 
dry  plates.  Let  all  your  operations  be  neat  and  rigor- 
ously clean. 

When  the  plates  have  been  prepared  as  above  de- 
scribed, and  are  quite  dry,  they  ought  to  present  a 
bright  and  polished  surface,  of  a  uniform  cream-like 
hue,  and  free  from  stains  and  pulverulent  deposit.  If  a 
plate  is  at  this  stage  streaky,  bluish  all  over,  or  in 
patches,  dull  (not  polished)  in  appearance,  or  troubled 
with  specks,  it  will  be  best  to  throw  such  a  plate  aside  ; 
whereas,  if  particles  of  matter  merely  are  deposited  on 
the  surface,  and  the  plate  in  other  respects  is  good, 
these  may  be  removed  by  a  soft,  flat  camel's  hair  pencil, 
or  by  means  of  a  tuft  of  cotton-wool.  Considerable  fric- 
tion may  be  applied  without  endangering  the  collodion 
film. 

As  soon  as  you  become  expert  in  the  manipulation 
of  dry  plates,  all  previous  coating  of  the  surfaces  or 
varnishing  of  the  edges  of  the  plate  may  be  omitted  ; 
but  in  this  case,  the  edges  of  the  sensitive  film  are  now, 
that  is,  when  the  plates  are  dried,  coated  with  a  solu- 
tion of  albumen,  and  dried  before  exposure.  If  you  use 
spirit  varnish  for  this  purpose,  it  is  preferable  to  post- 
pone varnishing  the  edges  until  the  plates  have  been 
exposed,  because  this  sort  of  varnish  is  apt  to  spread 
in  radiations  into  the  film  to  a  considerable  distance, 
especially  if  a  very  thin  varnish  is  employed,  and  to 
destroy  the  sensitiveness  of  the  adjoining  parts  of 
the  film. 

THE  PREPARATION   OF  DRY  PLATES  IN  COMMON  DAYLIGHT. 

The  discovery,  made  by  Poitevin  about  two  years  ago, 
that  tannin  is  a  sensitizer,  as  well  as  the  asserted  fact 
that  a  solution  of  an  iodide,  a  bromide,  or  a  chloride, 
when  poured  upon  a  collodion  plate  just  removed  from 


52 

the  silver  bath  and  washed,  destroys  sensitiveness,  has 
led  to  the  attempt  to  prepare  tannin  dry  plates,  in  a 
great  measure,  in  ordinary  daylight.  Thus  all  the 
operations  up  to  coating  the  plates  with  tannin  need 
not  be  performed  in  a  dark  room,  but  in  any  convenient 
and  comfortable  place  where  light  has  free  access  ;  the 
plates  are  prepared  up  to  this  stage,  and  then  stored 
away  in  a  dry  condition,  ready  to  be  sensitized  with 
tannin  when  required.  We  shall  briefly  describe  the 
operations. 

Clean  the  plates  as  usual,  and  coat  them  with  a  solu- 
tion of  albumen,  as  already  described,  and  allow  them 
to  dry.  Flow  over  the  collodion,  and  immerse  them  in 
the  silver  bath,  which  may  be  placed  in  any  convenient 
place  in  the  laboratory.  When  the  film  has  the  proper 
color  of  creaminess,  and  is  free  from  all  streaks  of  oil, 
remove  the  plate  from  the  bath,  and  wash  it  under  the 
tap  in  distilled  or  rain  water.  Immerse  it  now  in  a  bath 
of  bromide  of  potassium,  containing  about  four  grains 
of  the  salt  to  the  ounce  of  water,  and  let  it  remain  there 
for  a  few  seconds.  The  same  end  may  be  attained  by 
pouring  the  solution  of  bromide  of  potassium  two  or 
three  times  over  the  surface  of  the  washed  collodion 
film.  This  operation  is  intended  to  desensitize  the  film  ; 
and  this  is  effected,  in  all  probability,  by  the  removal  of 
all  free  nitrate  of  silver,  by  converting  it  into  bromide 
of  silver.  The  plate  is  finally  washed,  to  remove  the  re- 
sulting nitrate  of  potassa,  and  is  then  reared  away  to 
dry,  in  order  to  be  used  when  required.  The  plates,  at 
this  stage,  are  said  to  be  no  longer  sensitive  to  light, 
but  they  contain  a  collodion  film  containing  iodide  and 
bromide  of  silver,  one  or  both,  which  can  easily  be  made 
sensitive  by  coating  it  with  the  tannin  solution.  After 
the  film  is  thus  made  sensitive  it  has  to  be  kept  in  the 
dark  room,  or  away  from  all  access  of  light  until  ex- 
posed. 


THE  TANNIN  PROCESS.  53 

This  plan  of  preparing  dry  plates  was  first  proposed 
in  the  British  Journal  of  Photography,  if  we  remember 
right,  by  Professor  Himes,  and  followed  up  by  Mr.  J. 
Nicol,  in  the  same  journal.  With  all  due  respect  to 
such  authorities,  we  can  not  help  thinking  that,  if  a  sen- 
sitive plate  from  the  silver  bath  be  once  exposed  to 
light  for  a  moment,  a  change  will  take  place  in  the  film 
by  reason  of  the  free  nitrate  of  silver,  which  can  not 
easily  be  undone  by  any  coating  of  an  iodide,  bromide, 
or  chloride  afterward.  We  will  suppose,  however,  that 
they  do  desensitize  the  film  ;  and,  furthermore,  that  such 
a  plate  be  immersed  again  in  the  silver  bath  and  ex- 
posed in  the  ordinary  way  as  a  wet  plate.  What  is  the 
result  when  the  iron  developer  is  poured  upon  such  a 
a  plate  ?  The  whole  surface  becomes  immediately  black  ! 

When  the  plates  are  sensitized  with  the  tannin  solu- 
tion, however,  Professor  Himes  and  Mr.  Nicol  have  both 
produced  respectable  negatives — a  result  which  is  very 
anomalous  and  inexplicable,  when  compared  with  the 
effects  of  nitrate  of  silver  in  place  of  the  tannin. 

We  do  not  describe  the  above  method  for  general 
practice,  because  we  are  not  yet  assured  of  the  extent 
of  its  reliability. 


CHAPTER  IV. 

EXPOSING,  DEVELOPING,  FIXING,  AND  INTENSIFYING  THE  PLATES. 

IT  is  universally  admitted  that  the  dry  process  requires 
a  much  longer  exposure  than  the  wet  process  ;  from 
our  own  experiments  we  make  the  deduction  that  this 
exposure,  on  an  average,  is  at  least  six  times  longer 
with  the  former  than  with  the  latter.  There  seems  to 
be  a  mania  in  photographers  to  aim  rather  to  shorten  the 
time  of  exposure  than  to  get  good  results  ;  and,  owing 
to  this  morbid  desire  or  aim,  many  tannin  plates  turn 
out  to  be  so  much  trash.  Let  the  operator,  therefore, 
be  thoroughly  imbued  with  the  idea  that  a  tannin  plate 
is  slow  in  receiving  the  impression  ;  but  when  once  the 
impression  is  made,  it  can  be  developed.  Furthermore, 
let  him  understand  this  fact,  that  an  under-exposed 
tannin  plate  is  irremediable,  while  an  over-exposed  tan- 
nin plate  can  be  controlled,  and  the  image  developed 
accordingly. 

There  are  two  modes  of  development — the  acid  de- 
velopment, and  the  alkaline  development.  Our  preceding 
remarks  refer  to  the  ordinary  acid  developer.  With 
the  alkaline  developer  the  time  of  exposure  is  about 
twicelthat  with  the  wet  process.  Then  why  not  abandon 
the  acid  developer  at  once,  and  adopt  the  alkaline 
developer  in  general  practice  ? 

Because  the  alkaline  developer  is  apt  to  produce  a 
sort  of  fogginess,  which  detracts  from  the  beauty  of  the 
finished  negative,  and  because  many  photographers  as 
yet  have  failed  to  succeed  with  it.  As  a  rule,  we  prac- 
tice the  acid  development,  and  resort  to  the  alkaline 
only  in  special  cases,where  it  is  known  that  the  exposure 
has  been  necessarily  short. 


THE  TANNIN  PROCESS.  55 

Suppose  you  desire  to  take  a  negative  of  a  public 
edifice,  well  lighted,  and  reflecting  good  actinic  colors, 
arid  that  the  tannin  plate  has  been  quite  recently  pre- 
pared, the  exposure  may  be  at  least  one  minute.  A 
minute  and  a  half,  or  even  two  minutes,  in  all  probabil- 
ity, would  be  an  advantage.  For  an  ordinary  landscape 
an  exposure  of  about  three  minutes  will,  on  an  average, 
be  right.  The  lens  used  is  supposed  to  take  the  public 
edifice  above  mentioned  by  the  wet  process  in  about 
ten  seconds. 

We  recollect  instances  where  we  gave  an  exposure  of 
three  minutes  by  the  wet  process,  and  this  exposure 
was  found  requisite  to  obtain  an  impression  ;  in  such 
instances  as  these,  twenty  minutes  or  half  an  hour  will 
not  be  too  long  an  exposure  with  tannin  plates  ;  and 
yet  we  recollect  very  forcibly  that  at  one  time,  in  the 
infancy  of  our  acquaintance  with  the  tannin  process,  we 
attempted  to  obtain  pictures  on  tannin  plates  in  those 
localities  with  an  exposure  of  at  most  two  minutes,  and 
became  utterly  disgusted  with  tannin.  An  exposure  of 
twenty  minutes  may  appear  egregiously  long  to  portrait 
photographers  ;  but  let  them  not  be  deterred  from  land- 
scape photography  before  they  have  balanced  accounts. 
With  the  wet  process  in  the  field,  each  negative  will  re- 
quire, on  an  average,  half  an  hour  before  it  is  finished, 
or  in  a  condition  to  be  carried  from  the  field  ;  with  the 
dry  process,  the  impression  can  be  made,  on  an  average, 
in  ten  minutes.  It  is  evident,  therefore,  that  more  neg- 
atives can  be  taken  on  a  tour  by  the  dry  than  by  the 
wet  process,  in  a  given  time.  The  difference  in  favor 
of  the  wet  process  is,  firstly,  that  the  negatives  can  be 
examined  before  leaving  the  ground,  and  fresh  ones 
taken  if  the  first  are  defective  ;  and,  secondly,  the  neg- 
atives are,  comparatively  speaking,  finished,  while  those 
by  the  dry  process  have  to  be  developed  at  some  future 


56 


OR, 


time.  The  above  maybe  advantages  on  the  side  of  the 
wet  process,  but  their  absence  in  the  dry  process  can 
scarcely  be  called  disadvantages. 

RULES  FOR  EXPOSURE. 

1.  Let  a  minute  or  a  minute  and  a  half  be  the  minimum 
exposure  for  a  well-lighted  object,  such  as  buildings, 
ships,  etc. 

2.  Give  three  minutes  for  a  well-lighted  landscape. 

3.  A  quarter  of  an  hour  to  twenty  minutes  will  be  re- 
quired in  deep  ravines  or  shady  groves. 

4.  When  traveling  on  cars,  and  stepping  out  at  the 
different  stations  to  take  views,  expose  in  accordance 
with  the  above  rules  where  it  is  possible  ;  where  the 
exposures  are  necessarily  shorter  than  the  times  above 
mentioned,  mark  the  negatives  with  some  sign  by  which 
you  know  that  they  are  to  be  developed  by -the  alkaline 
developer. 

5.  Affix  on  each  negative  a  small  ticket,  upon  which 
is  written  the  time  of  exposure. 

ACID  DEVELOPMENT. 

Pyrogallic  acid  is  the  developer  used  in  the  tannin 
process.  Its  action  alone  is  much  too  energetic  without 
the  restraining  influence  of  some  other  acid.  Either 
acetic  or  citric  acid  may  be  used  for  this  purpose.  We 
have,  therefore,  two  acid  developers,  either  of  which 
can  be  used.  The  color  of  the  finished  negative  is  dif- 
ferent in  the  two  cases  ;  with  acetic  acid  the  hue  inclines 
more  to  the  red  than  with  citric  acid,  which  has  a 
tendency  to  produce  a  bluish  tone. 

TO  DEVELOP  WITH  ACETO-PYROGALLIC  ACID. 

This  method  is  the  simplest  of  the  two,  because 
acetic  acid  is  in  the  hands  of  all  photographers.  Make 
the  solutions  in  stock  bottles  : 


THE  TANNIN  PROCESS.  57 

ACID  PYROGALLIC. 


No    1    i  Py™!?^0  a°id     •         •         .18  grains. 
(  Acetic  acid        .        .         .  1  ounce. 

>j      o    f  Nitrate  of  silver    .         .         .30  grains. 

(  Distilled  or  rain  water      .          1  ounce. 

No.  3.      Acetic  acid    .  +.        .       1  ounce. 

Place  these  bottles  on  a  shelf  in  the  dark  room  con- 
veniently at  hand  for  use.  When  a  picture  has  to  be 
developed,  as,  for  instance,  a  stereoscopic  plate,  make 
the  following  solution  : 

Of  No.  1  .        ...        .15  drops. 

Rain  or  distilled  water     .         .  3  drachms. 

Of  No.  2     .        .         .        .        .4  drops. 

Shake  the  mixture  well  and  pour  it  upon  the  collodion 
film,  after  it  has  first  been  made  uniformly  moist  by 
dipping  the  plate  in  a  dish  of  clean  water.  If  the  picture 
flashes  out  rapidly,  the  exposure  has  been  too  long,  in 
which  case  a  few  drops  of  No.  3  are  to  be  added  to  the 
developer,  to  restrain  its  action.  The  picture  is  most 
.successful  when  the  action  of  the  developer  does  not 
instantly  appear,  and  after  it  does  commence  if  the 
progress  is  slow.  As  soon  as  the  picture  is  completely 
out,  and  the  developer  has  become  red,  it  will  be  neces- 
sary to  make  a  fresh  quantity,  and  proceed  until  the 
shadows  are  sufficiently  intense.  Avoid,  as  much  as 
possible,  rapidity  of  action  in  the  developer,  because 
rapid  action  is  merely  another  mode  of  expression  for 
heavy  deposit,  which  is  generally  quite  granular  —  a 
condition  to  be  avoided.  Well-exposed  pictures  have 
always,  at  this  stage,  a  rich  reddish  tone  when  developed 
with  the  aceto-pyrogallic  acid.  The  developer  soon 
turns  red  if  much  silver  is  added,  or  too  little  acetic  acid 
be  used. 


58 


TO    DEVELOP    WITH    CITRO-PYROGALLIC    ACID. 

This  is  the  more  general  mode  of  developing  a  tannin 
plate  of  the  two  j  for  which  purpose  make  the  following 
stock  solutions : 

f  Pyrogallic  acid.     .         .         .96  grains. 
No.  1.   ]  Absolute  alcohol         .         /          1  ounce. 

I  Ether     .  7        .         .       2  or  3  drops. 

Five   minims  of  this  solution  contain  one  grain  of 
.  pyrogallic  acid. 

f  Nitrate  of  silver    .         .         .     10  grains. 

No.  2.   J  Citric  acid        '  .         .         .         40  grains. 

I  Distilled  water     ...       1  ounce. 

No  3     i  Citric  acid     .         .         .         .60  grains. 
( Distilled  water  .         .          1  ounce. 

Moisten  the  film  as  before,  by  dipping  the  plate  into 
a  dish  of  clean  water  ;  then  make  the  following  mix- 
ture : 

Distilled  or  rain  water         .         .     3  drachms. 
Of  No.  1  .         .         .         .         2  drops. 

Of  No.  2      .         .         .         .         .2  drops. 

Shake  the  mixture,  and  pour  it  upon  the  moistened 
film.  If  the  action  is  slow,  by  reason  of  the  inadequate 
exposure,  add  more  of  the  alcoholic  pyrogallic  acid, 
and  proceed  pouring  on  and  off  until  the  picture  is 
thoroughly  out.  On  the  contrary,  if  the  action  is  too 
rapid,  it  must  be  restrained  by  the  addition  of  a  drop 
or  two  of  No.  3. 

Intensity  is  produced  by  the  citro-nitrate  of  silver. 

Owing  to  the  volatility  of  pyrogallic  acid  in  a  con- 
centrated solution  of  alcohol,  it  is  preferable  to  use 
a  more  diluted  solution,  and  not  to  prepare  a  large 
quantity  at  a  time.  For  this  purpose  the  following 
formulas~are  better  adapted,  and  at  the  same  time  are 
more  manageable  in  other  respects  : 


THE  TANNIN  PROCESS.  59 

(•  Pyrogallic  acid          .         .     30  grains. 
No.  1.   4  Alcohol  ...  4  drachms. 

I  Water        ....       4  drachms. 
Sixteen  minims  of  this  solution  contain  one  grain  of 
pyrogallic  acid.     It  will  be  necessary  and  convenient 
to  have  a  drachm  glass  ready  at  hand  for  this  measur- 
ing, and  the  following  solutions  : 
XT     0     f  Citric  acid    ,  2  drachms. 

IN  0.  A.     -\  •     .        '"   •    *        "     . 

( Distilled  or  rain  water     .         4  ounces. 


Sixteen  mmims  of  this  solution  contain  in  like  man- 
ner one  grain  of  citric  acid.      ''''•.$''*-. 
•XT     o     f  Nitrate  of  silver    .  V-Vi-v'10  grains «^^1 


1  Rain  or  distilled  water      •  V>* .  1 
No.  4.       Distilled  or  rain  water  .     1  pint. 

If,  for  instance,  a  stereoscopic  picture  is  to  be  de- 
veloped, take  an  ounce  vial  and  pour  into  it  half  an 
ounce  of  the  distilled  water,  to  this  add  live  minims  of 
No.  1,  ten  minims  of  No.  2,  previously  mixed  with 
one  qr  two  drops  of  No.  3.  Shake  the  mixture  well  and 
then  pour  it  upon  the  moistened  plate.  If  the  image 
comes  out  slowly,  add  more  pyrogallic  acid  ;  if  there  is 
a  want  of  intensity,  after  the  image  appears,  add  more 
of  No.  3  ;  if  there  is  a  tendency  to  fogging,  add  more 
of  No.  2,  or  wash  the  plate  gently  and  flow  it  with  the 
bromide  solution  previously  recommended  and  used  in 
preparing  the  tannin  plates,  and  then  proceed  again 
with  the  developer.  The  full  intensity  can  be  brought 
out,  after  a  little  practice,  before  fixing  ;  but  we  find  it 
generally  more  convenient  to  re-intensify  after  the 
image  has  been  fixed  and  well  washed.  The  same 
solutions  can  be  used  as  for  the  development  to  produce 
the  desired  effect,  or  the  Selle's  new  intensifier  may  be 
employed.  This  solution  produces  a  reddish  brown 
negative,  which  prints  well. 


60  DRY  PLATE  PHOTOGRAPHY  ;  OR, 

SELLE'S  INTENSIFIER. 

v-     i     ( Sulphate  of  uranium     .         .10  grains. 
( Distilled  or  rain  water      .          1  ounce. 

iq.     o     ( Ferridcyanide  of  potassium      .     10  grains. 
( Distilled  or  rain  water          .  1  ounce. 

Take  one  drachm  of  each  of  these  solutions,  mix  them 
well  together,  and  flow  the  developed  and  well-washed 
plate  with  the  mixture,  the  image  will  soon  redden  and 
assume  sufficient  intensity,  which  must  be  somewhat 
deeper  than  is  finally  required,  because  the  shades  be- 
come more  transparent  from  the  effect  of  the  varnish. 

Pyrogallic  acid  solution  should  always  be  filtered 
immediately  before  use,  otherwise  any  particles  of  mat- 
ter that  may  chance  to  be  present,  from  retaining  the 
acid  in  a  more  concentrated  form  CAren  in  the  midst  of 
the  dilution,  are  apt  to  produce  in  the  development  ir- 
regularities that  are  exceedingly  disagreeable  after  all 
the  trouble  that  has  been  taken  in  the  preparation  of 
the  plates. 

If  the  prepared  tannin  plates  have  not  received  a 
substratum  of  albumen,  gelatine,  or  gutta-percha,  there 
is  always,  more  or  less,  a  tendency  in  the  film  to  split  up 
and  peel  off.  To  avoid  this  it  has  been  recommended, 
and  we  always  pursue  the  plan  oursel  7es  in  the  cases 
here  comprehended,  to  flow  the  exposed  plate  just  before 
development  with  a  mixture  of  equal  portions  of  alcohol 
and  water,  and  then  to  gently  wash  off  the  apparent 
oily  markings  of  this  mixture  with  water  before  pouring 
on  the  developer.  This  alcoholic  solution  renders  the 
film  more  porous,  and  retains  it  on  the  glass.  With  a 
substratum  it  is  unnecessary. 

During  the  development,  if  the  solution  becomes  in 
any  degree  turbid,  it  is  advisable  to  throw  it  away,  and 
mix  a  fresh  quantity  ;  for  the  turbidity  is  owing  to  a 


THE  TANNIN   PROCESS.  61 

decomposition,  by  which  particles  of  silver,  etc.,  are  fre- 
quently deposited  on  the  negative,  giving  it  a  granular 
appearance  ;  and  this  same  appearance  is,  in  such  a  con- 
dition, reproduced  on  the  paper  print. 

The  development  of  a  tannin  picture  by  any  of  the 
acid  solutions  just  given  is  sometimes  protracted, 
especially  when  the  plate  has  been  under-exposed  ;  in 
such  a  case  as  this  it  becomes  tedious  to  retain  the  plate 
in  the  hand  during  so  long  an  operation.  For  this  pur- 
pose leveling  stands  are  constructed,  on  which  the  plates 
may  be  placed  and  left  with  the  developing  solution 
upon  it  until  the  proper  intensity  has  been  attained. 

A  leveling  stand  may  be  constructed  of  two  discs  of 
thin  wood  and  an  axis  between  them,  the  combination 
having  the  appearance  of  a  spool  or  bobbin.  The  upper 
disc  is  two  inches  in  diameter,  the  lower  four  inches  ; 
the  length  of  the  axis  four  inches.  A  circle  is  turned 
in  the  lower  disc  three  inches  and  a  half  from  the  centre, 
and  three  screws  perforate  this  circle  at  points  seven 
inches  apart  ;  the  ends  of  the  screws  are  filed  flat. 

The  plate  is  placed  upon  the  stand,  and  the  developer 
is  poured  upon  it ;  if  the  latter  does  not  run  off  the 
plate,  but  is  retained  in  an  equal  film  upon  its  whole 
surface,  the  stand  is  level,  and  requires  no  adjustment  ; 
but  if  the  developer  flows  toward  one  corner,  the  stand 
is  not  level,  and  must  be  adjusted  by  means  of  the 
screws.  We  will  suppose  the  fluid  on  the  plate  accumu- 
lates right  over  one  of  the  three  screws,  it  is  evident 
this  side  is  lower  ;  in  order  to  raise  it,  turn  round  the 
screw  forward  until  the  adjustment  is  made,  and  the 
surface  of  the  plate  is  horizontal. 

By  means  of  a  number  of  leveling  stands  several 
negatives  can  be  developed  at  the  same  time,  by  which 
means  much  time  and  labor  are  spared. 

As  the  amateur  or  practical  operator  becomes  more 
3 


62  DRY  PLATE  PHOTOGRAPHY  J   OR, 

and  more  acquainted  with  landscape  photography,  cer- 
tain forms  of  development  will  occur  around  the  edges 
of  trees,  mountains,  etc.,  in  which  there  is  an  encroach- 
ment of  the  high  lights  around  the  edges,  as  if  the  light 
had  been  inflected  or  diffracted,  that  is,  had  not  pro- 
ceeded in  straight  lines,  but  had  been  broken  around 
these  corners  and  edges.  This  encroachment  depends 
in  a  great  measure  upon  the  direction  of  the  light ;  for 
if  the  sun  be  located  in  the  hemisphere  behind  the 
camera,  it  seldom  or  ever  occurs  ;  but  if  in  the  opposite 
hemisphere,  frequent  examples  of  blurring  or  halation 
of  the  negative  will  be  met  with.  But  the  position  of 
the  sun's  rays  is  not  the  only  cause  of  the  trouble  in 
question.  A  plate  of  glass  has  two  reflecting  surfaces ; 
light  impinging  upon  the  first  surface  coincides  by  re- 
flection with  that  which  impinges  on  the  collodion  film  ; 
whereas,  the  rays  which  are  reflected  from  the  second 
surface  and  again  impinge  upon  the  collodion  film  do 
n-ot  fall  upon  the  parts  they  passed  through,  and  con- 
sequently give,  rise  to  the  encroachment  alluded  to. 

This  sort  of  blurring  is  obviated  in  a  great  measure, 
if  not  totally,  by  rendering  the  rays  reflected  from  the 
posterior  surface  of  the  plate  non-actinic,  which  is  ef- 
fected by  placing  behind  the  plate  during  exposure  a 
piece  of  orange-colored  blotting  pap^r,  or  other  con- 
venient material.  The  author  finds  a  thin  layer  of  the 
red  sheet  of  rubber,  such  as  is  used  by  dentists  for  mak- 
ing artificial  palates,  etc.,  to  be  the  best.  Such  a  sheet 
can  be  pressed  out  very  thin  on  a  plate  of  glass,  of  the 
size  of  the  stereoscopic  plate,  for  instance,  and  thus 
kept  ready  for  use  to  be  placed  in  apposition  with  the 
back  of  the  tannin  plate  when  exposed.  The  rays  of 
light,  after  penetrating  the  collodion  film,  impinge  on 
this  orange-colored  film,  whereby  only  orange-colored 
light  is  turned  back  upon  the  collodion  film,  and,  being 
non-actinic,  they  make  no  impression. 


THE  TANNIN  PROCESS.  63 

FIXING  SOLUTION  FOR  TANNIN    NEGATIVES. 

Hyposulphite  of  soda  ...       5  ounces. 
Water      .         .         .         .        .         10  ounces. 

This  solution  can  be  used  over  and  over  again,  the 
strength  being  kept  up  by  the  addition  of  fresh  crystals 
when  required.  Great  care  must  be  taken  to  remove 
this  salt  from  the  film  by  washing  thoroughly,  first  in 
rain  water  and  then  in  a  dilute  solution  of  common  salt, 
before  the  plates  are  submitted  to  the  action  of  the  in- 
tensifier  or  put  away  to  dry. 

ALKALINE  DEVELOPMENT. 

As  soon  as  the  operator  is  quite  at  home  in  all  the 
manipulations  of  the  acid  development,  he  may  try  his 
hand  at  the  alkaline  development ;  for,  although  per- 
haps he  may  not  wish  to  practice  the  latter  mode  in 
preference  to  the  former,  times  will  occur  in  which  the 
latter  will  have  to  be  resorted  to  in  spite  of  every  pre- 
caution to  the  contrary. 

Some  operators  prefer  the  alkaline  development ;  the 
majority,  however,  adhere  to  the  old  reliable  process  of 
aceto-  or  citro-pyrogallic  acid.  The  time  of  exposure 
with  this  developer  is  much  shorter  than  by  the  acid 
developer,  but  not  so  short  as  with  the  wet  process.  If 
by  the  wet  process,  with  a  given  lens,  diaphragm,  and 
light,  an  exposure  of  four  seconds  will  produce  a  given 
result,  with  a  tannin  plate  and  the  alkaline  developer 
the  same  result  can  be  obtained  in  about  ten  or  twelve 
seconds, 

Prepare  the  following  solutions  : 

DILUTE  ALCOHOL. 

( Alcohol  .         .         .  .     2  ounces. 

1  Distilled  or  rain  water  2  ounces. 


64  DRY  PLATE  PHOTOGRAPHY  J  OR, 

ALKALINE  DEVELOPER. 

(  Carbonate  of  ammonia  .         .48  grains, 
(Water        .        .        V  '    V        3  ounces. 
One  drachm  of  this  solution  contains  two  grains  of 
the  carbonate  of  ammonia. 

PYROGALLIC  ACID  SOLUTION. 

f  Pyrogallic  acid   , .  .30  grains. 

No.  3.  j  Alcohol      .         .     .;*...;.:«;•.:       4  drachms. 

I  Water  .         .         .     -^ »..-.,  ;.,      4  drachms. 
Sixteen  minims  of  this  solution  contain  one  grain  of 
pyrogallic  acid. 

NITRATE  OF  SILVER  SOLUTION. 

C  Nitrate  of  silver    .        .        .10  grains. 
°*    '    i  Distilled  or  rain  water      .          1  ounce. 

SOLUTION  OF  CITRIC  ACID. 

j  Citric  acid    ....     2  drachms. 
°*    '    I Distilled  or  rain  water     .         4  ounces. 

* 
No.  6.      Distilled  or  rain  water          .     1  pint. 

FIRST  OPERATION. 

As  soon  as  the  plate  is  removed  from  the  holder,  flow 
over  the  surface  a  sufficient  quantity  of  'Jie  dilute  alco- 
hol No.  1,  and  then  let  the  solution  drain  back  again  into 
the  vial  ;  afterward  gently  wash  the  film  until  the  oily 
streaks  disappear,  and  the  water  flows  uniformly  over 
the  surface  of  the  collodion. 

SECOND  OPERATION. 

In  a  two-ounce  vial  mix  one  drachm  of  the  alkaline 
solution  No.  2  with  seven  drachms  of  water,  and  cover 
the  plate  with  this  mixture  ;  now  pour  it  back  again 
into  the  vial,  and  add  thereto  five  minims  of  the  alco- 


THE   TANNIN   PROCESS.  65 

holic  solution  of  pyrogallic  acid  No.  3.  Shake  the  mix- 
ture well  up  and  pour  it  upon  the  plate.  The  picture  will 
soon  begin  to  appear,  if  the  exposure  has  been  long 
enough.  If  it  is  slow  in  appearing,  add  two  or  three 
minims  more  of  No.  3.  If  by  this  addition  the  picture 
does  not  appear  in  a  minute  or  less,  the  exposure  has 
been  too  short,  and,  although  eventually  a  picture  may 
be  brought  out,  it  will  fail  to  contain  the  requisite 
amount  of  detail  to  entitle  it  to  be  called  satisfactory  ; 
it  will  be  a  black  and  white  picture. 

But  we  will  suppose  the  picture  begins  to  appear 
almost  immediately,  and  proceeds  gradually,  receiving 
more  and  more  detail,  until  finally  it  is  perfect  in  this 
respect,  although  far  from  being  intense  ;  in  fact,  at  this 
stage,  it  is  a  faint  reddish  colored  negative,  perfect  in 
all  its  parts,  and  requiring  only  intensification.  Such 
is  the  normal  result ;  but  the  picture  may  flash  out  red 
almost  immediately.  In  this  case  the  exposure  has  been 
too  long,  and  to  remedy  this,  wash  off  the  developer  im- 
mediately, and  use  only  the  acid  developer  in  the  sub- 
sequent treatment.  With  the  normal  condition  proceed 
as  follows  : 

THIRD  OPERATION. 

Pour  off  the  alkaline  developer  and  wash  the  plate 
gently,  and  then  flow  it  with  the  following  solution,  in 
order  to  remove  all  alkalinity : 

Solution  of  citric  acid  No.  5        .     30  minims. 

Water     .....          3  drachms. 

Pour  this  solution  away,  and  flow  the  plate  with  the 
following  : 

Distilled  water      .         .       4  drachms. 
Pyrogallic  acid,  No.  3          5  minims. 
Citric  acid,  No.  5          .10  minims. )  previously 
Nit.  c  f  silver,  No.  4      2  to  3  minims. )     mixed. 


66  DRY  PLATE  PHOTOGRAPHY  ;    OR, 

Shake  the  mixture  well,  and  proceed  exactly  in  the 
same  mariner  as  with  the  acid  developer,  as  already  de- 
scribed. The  washing,  fixing,  etc.,  from  this  stage,  are 
also  precisely  the  same. 

Cyanide  of  potassium  in  solution  is  not  to  be  recom- 
mended as  a  fixing  agent,  because  it  soon  penetrates 
the  collodion  film,  and  then  seems  to  disorganize  the 
stratum  of  albumen  or  gelatine  beneath  it,  and  to  pro- 
duce bubbles  and  other  irregularities  in  the  film  that 
deteriorate  the  picture.  But  if  the  tannin  picture  is 
somewhat  fogged,  it  maybe  clarified  in  a  great  measure, 
and  rendered  tolerably  passable,  in  the  following  manner, 
in  which  cyanide  of  potassium  is  brought  into  play  : 

CLARIFYING  A  TANNIN  NEGATIVE. 

Make  the  following  solutions  : 

TINCTURE  OF  IODINE. 

•XT      i     f  Iodine  .         .         .         .         .30  grains. 

1  Alcohol      ....          1  ounce.         ."|L 

CYANIDE  OF  POTASSIUM  SOLUTION. 

No    2    I  ^van^e  °f  potassium.  .         .       1  drachm. 
(Rain-water         ...  4  ounces. 

If  the  film  is  but  slightly  fogged,  flow  it  with  4  drachms 
of  water  containing  20  minims  of  tincture  of  iodine  for 
a  short  time.  This  dilute  solution  of  iodine  may  be  used 
several  times  in  succession,  until  its  color  has  almost 
entirely  vanished.  Wash  the  film,  and  flow  over  it  a 
sufficient  quantity  of  the  solution  of  cyanide  of  potas- 
sium. This  is  very  rapid  in  its  action  on  the  iodide  of 
silver,  and  soon  clarifies  the  negative.  With  cautious 
manipulation,  such  an  expedient  may  be  resorted  to  with 
advantage  ;  but  in  general  it  produces  harsh  negatives 
in  which  the  finest  markings  have  been  destroyed,  and 


THE  TANNIN   PROCESS.  6T 

nothing  but  lights  and  shades  remain  in  stern  contrast, 
without  all  intermediate  gradation  to  give  harmony  to 
the  subject.  A  stronger  solution  of  the  tincture  of 
iodine  is  necessary  to  remove  stains  from  the  corners  of 
negatives  ;  even  that  in  the  undiluted  form  of  No.  1 
will  not  be  too  strong.  Care,  however,  must  be  taken 
that  it  does  not  flow  any  further  upon  the  negative  than 
is  requisite  by  the  extent  of  the  stain ;  the  place  is 
then  washed  and  treated  with  the  cyanide  solution,  as 
before. 


CHAPTER  V. 

CHANGING  BOXES  FOB  LANDSCAPE  PHOTOGRAPHY. 

THE  tourist  having  now  learned  how  to  prepare  and 
develop  dry  plates,  is  desirous  of  making  practical  ap- 
plication of  his  knowledge.  But  now  arises  in  his  mind, 
for  the  first  time,  probably,  a  difficulty  regarding  the 
transportation  of  the  dry  plates,  and  the  separation  of  a 
single  plate  from  the  package,  without  endangering  the 
sensitiveness  of  the  rest.  If  the  plates  have  been  well 
packed,  as  already  described  in  a  previous  chapter,  they 
will  bear  change  of  locality  to  any  extent,  from  the 
meridian,  passing  through  the  Cape  of  Good  Hope,  right 
round  the  earth  on  a  parallel  of  latitude  to  the  place  of 
beginning,  as  long  as  light  is  not  admitted  into  the  in- 
terior. A  plate,  therefore,  can  be  separated  from  the 
rest  in  a  dark  room  ;  this  expedient  is  very  inconvenient 
in  traveling,  and  frequently  impracticable.  Plans,  con- 
sequently, have  been  devised  for  the  manufacture  of 
what  are  denominated  changing  boxes,  which  are  so 
constructed  as  to  contain  a  given  number  of  dry  plates, 
and  to  allow  a  single  plate  to  be  withdrawn  from  its 
receptacle  in  the  changing  box,  and  transferred,  without 
ever  coming  into  the  light,  into  the  plate-holder  for 
exposure  ;  and,  after  exposure,  to  be  transferred  back 
again  into  its  receptacle  in  the  changing  box.  Up  to 
the  present  time  we  have  been  using  a  changing  box  of 
our  own  invention  and  construction,  and  we  have  found 
it,  like  all  the  wonderful  things  we  imagine,  concoct 
from  ideas,  and  put  together  ourselves,  wonderfully  ap- 
propriate and  everlastingly  strong.  There  is  no  end  to 


THE   TANNIN   PROCESS.  69 

the  wear  and  tear  it  will  endure.  The  model  locomotive 
we  made  in  1832,  christened  "Fury,"  is  still  a  vigorous 
little  tug  ;  the  French  bedstead,  the  chest  of  drawers, 
the  eccentric  chuck,  the  slide  rest,  the  overhead  motion, 
the  spinning-jenny,  the  fringe-loom,  and  hundreds  of 
other  ebullitions  of  the  untired  brain  and  the  never- 
flagging  hand,  as  they  meet  our  view  at  every  moment, 
attest  to  the  permanency  of  home-fabrications.  But 
such  fabrications  are  not  always  the  best ;  and  if  they 
were,  we  have  no  time  to  work  mechanically  for  our 
neighbors,  unless  it  be  to  open  a  gate  for  our  betters 
to  drive  through. 

Our  own  changing  box,  as  previously  observed,  is 
very  appropriate  for  the  ends  in  view,  and  very  strong  ; 
it  will  contain  twenty-five  dry  plates,  each  of  which  can 
be  taken  out  and  placed  in  the  plate-holder,  and  again 
replaced  in  its  former  position,  or  elsewhere,  without 
any  access  of  light.  The  operation,  too,  is  easy.  But 
the  box  is  somewhat  cumbersome.  It  seems  to  strike 
us  forcibly  that  Nelson  Wright,  Esq.,  of  New  York, 
who  is  the  sole  proprietor  of  John  and  Jacob  Stock's 
patent  changing  box  for  dry  plates,  must  either  have 
seen  or  heard  of  our  conception  and  construction  ;  he 
sent  us  one  of  his  patent  boxes,  which  we  placed  in 
juxta-position  with  our  own.  Imagine  Barnum's  giant 
and  Tom  Thumb  walking  arm  in  arm  together,  or  Mount 
Etna  and  a  funeral  mound  collocated  side  by  side  ;  such 
is  the  contrast  between  the  two  boxes.  We  have  put 
away  our  own  invention  for  awhile,  and  have  lately 
been  experimenting  with  the  new  comer.  We  must 
acknowledge  (and  we  certainly  at  the  beginning  were 
determined  not  to  make  any  such  admission)  that  the 
new  changing  box  is  very  appropriate,  very  strong,  and 
very  compact ;  it  performs  all  that  it  promises.  All  the 
paraphernalia  of  a  photographic  tour  may  now  be  carried 
3* 


Oil, 

with  ease  in  two  small  packages,  one  for  either  hand  ; 
the  camera  and  holder  in  one  hand,  and  the  changing 
box  and  tripod  in  the  other.  Such  an  arrangement  is 
truly  a  multum  in  parvo,  a  concentration  of  all  the 
separate  states  in  a  unity,  as  it  should  be. 

DESCRIPTION  OF  THE  PATENT  DRY  PLATE  BOX  AND  SHIELD. 

As  the  name  implies,  there  are 
two  parts  in  this  arrangement,  the 
one  for  containing  a  given  number 
of  dry  plates,  protected  against  the 
light ;  and  the  other  the  holder  or 
shield,  for  exposing  each  plate 
when  required. 

The  accompanying  figure  repre- 
sents the  changing  box,  surmount- 
ed by  the  plate-holder,  which  slides 
endwise  in  a  groove  on  the  top  of 
the  second  lid   of  the   box.     The 
changing   box  itself  is  in  the  form  of  a  rectangular 
prism,  containing  on  two  opposite  sides,  within,  twelve 
or  eighteen  grooves  for  the  reception  of  so  many  dry 
plates,  and  is  closed  on  the  top  by  means  of  two  doors 
sliding  in  opposite  directions.     On  one  side  at  the  top 
is  found  a  rack  furnished  with  as  many  dents  as  the 
box   contains   plates  ;   this   rack   of  brass  is  pressed  • 
upward  by  means  of  a  spring  beneath  against  a  pro- 
jecting tooth  or  cog  fitted  upon  the  side  of  the  upper 
sliding  door.    On  this  upper  slide  is  fixed  a  brass  groove, 
into  which  the  end  of  the  plate-holder  slides,  and  as  this 
end  slides  into  its  place  it  opens  a  brass  door,  beneath 
which  closes  an  incision  immediately  above  a  dry  plate; 
an  incision  similar  to  the  preceding,  which  is  sufficiently 
large  to  allow  a  dry  plate  to   slip  easily  through,  is 


THE  TANNIN  PROCESS.  71 

found  on  the  end  of  the  plate -holder,  and  coincides  in 
position  with  the  former  incision.  By  pressing  down 
the  spring  rack,  the  upper  plate  may  be  slidden  so  that 
the  tooth  may  catch  in  each  indentation,  which  thus 
brings  the  incision  successively  over  each  dry  plate  be- 
neath. But  the  plate  beneath  can  not  escape  until  the 
under  slide  is  drawn  out  as  far  as  it  can  be  drawn,  and 
until  a  spring  on  its  upper  surface  rises  and  stops  its 
motion  backward.  When  in  this  position  the  passage 
for  a  dry  plate  is  clear  ;  and  by  inverting  the  box  with 
the  plate-holder  on  its  end,  the  dry  plate  immediately 
above  the  open  incision  will  fall  down  and  through 
these  incisions  into  the  plate-holder  beneath,  where  it  is 
secured  by  means  of  a  cross-bar  on  the  back  of  the 
plate-holder,  which  presses  down  a  door  that  closes  up 
the  incision  at  the  end,  and  pushes  the  plate  firmly  for- 
ward upon  the  ledges  of  the  groove  in  which  it  slides. 
As  soon  as  this  door  is  closed  and  the  changing  box 
inverted,  or  turned  right  side  up,  the  spring  on  the 
under  slide  on  the  top  of  the  changing  box  is  pressed 
down,  which  allows  the  under  slide  to  be  pushed  back 
into  its  place  so  as  to  close  up  all  avenues  for  light 
to  enter.  When  this  is  done  the  plate-holder  is  re*- 
moved  from  its  connection  with  the  changing  box,  and 
is  ready  to  be  transferred  to  the  camera  for  exposure. 
After  exposure  the  connection  is  again  made,  the  under 
slide  again  drawn  out  to  its  extremity,  and  the  exposed 
plate  is  allowed  to  drop  down  into  its  former  position. 
The  same  order  is  observed  with  each  plate. 

In  the  figure  the  under  slide  is  marked  3,  the  upper 
one  2,  and  the  plate  box  1. 

The  collodion  film  of  each  plate  looks  always  in  the 
same  direction  ;  toward  the  number  3. 

To  fill  the  box  with  plates  the  screw  at  the  end  2  is 


72  DRY  PLATE  PHOTOGRAPHY  ;  OR, 

removed,  the  rack  is  pressed  down,  and  the  two  slides 
are  drawn  out. 

We  have  seen  other  forms  of  changing  boxes,  but  we 
give  preference  to  this  one,  by  reason  of  its  compact 
form,  its  superior  adaptability  for  the  purposes  in  view, 
and  the  absence  of  any  liability  to  get  out  of  order  from 
common  wear  and  tear. 


CHAPTER   VI. 

PREPARATION    OP    TRANSPARENT     POSITIVES     BY     THE     TANNIN 
PROCESS,  OR  CONTACT-PRINTING  ON  GLASS. 

CONTACT-PRINTING  on  glass  is  one  of  the  most  attractive 
applications  of  photography ;  it  is  attractive  because 
the  results  are  among  the  finest  specimens  of  the  art ;  it 
is  attractive,  too,  because  the  operation  can  be  per- 
formed at  all  seasons  of  the  year,  and  by  artificial  as 
well  as  solar  light  ;  it  is  an  amusement  in  winter,  and 
a  recreatiion  during  the  evenings  after  business.  It  is, 
finally,  an  easy  operation. 

Negatives  are  required  in  this  mode  of  printing  of  the 
same  nature  and  perfection  as  for  printing  on  paper, 
with  this  single  condition,  an  indispensable  condition  f 
that  the  negative  plate  be  perfectly  fiat  or  horizontal. 
Ground  plate-glass,  must,  therefore,  be  the  receptacle  of 
the  negative  film  for  all  operations  of  printing  on  glass 
by  the  dry  process. 

We  need  scarcely  remark,  that  negatives  for  this  sort 
of  printing  must  be  clear,  bright,  vigorous,  full  of  detail, 
and,  if  we  may  be  allowed  to  be  pleonastic,  totally  free 
from  fogging ;  for  these  are  the  conditions  of  every 
good  negative,  and  without  them  no  good  print  can  be 
obtained  either  on  paper  or  glass. 

The  varnish  with  which  such  negatives  are  coated 
must  be  quite  free  from  all  particles  of  dust  or  other 
substance,  which,  when  dry  upon  the  film,  might  cause 
inequalities  that  would  prevent  perfect  contact  between 
the  negative  and  the  positive  films.  The  edges,  too,  of 
the  negative,  on  which  the  collodion  arid  varnish  have 
passed  off  from  the  plate,  are  frequently  elevated  by  a 


74  DRY  PLATE  PHOTOGRAPHY  J    OR, 

ridge  of  one  or  both  these  media  ;  this  ridge  will  also 
prevent  contact  between  the  plates,  and  must  be  re- 
moved by  cutting  off  a  slip  of  glass  on  one  side  and  end 
by  means  of  the  diamond,  or  by  abrading  the  elevated 
part  by  means  of  a  pen-knife.  Perfect  contact  is  abso- 
lutely required  between  the  two  films  ;  such  precau- 
tions, therefore,  are  also  absolutely  required  in  the 
preparation  of  the  negative  plates.  The  same  conditions 
are  also  necessary  in  the  prepared  tannin  plates  ;  but 
here  no  varnish  has  been  used,  and,  if  a  substratum  of 
albumen  has  been  employed,  the  elevated  ridges  can 
easily  be  removed  by  abrasion  or  the  diamond,  without 
any  detriment  to  the  film  afterward  ;  but  if  the  edges 
of  the  tannin  plate  have  alone  been  varnished,  it  is 
evident  that  the  removal  of  the  ridge,  either  by  scratch- 
ing off  or  by  cutting  with  the  diamond,  would  expose 
the  film  to  slip  off  in  the  subsequent  treatment  with 
the  developer.  The  best  precaution,  consequently,  is 
to  use  rather  a  thin  collodion  in  the  preparation  of  the 
tannin  plates,  and  to  obviate  the  ridges  in  question  by 
a  skillful  manipulation. 

The  ordinary  printing  frame  is  employed  for  this  sort 
of  printing  ;  but  do  not  forget  this  difference  in  its  em- 
ployment :  the  glass  to  receive  the  print  is  never  brought 
out  into  the  light  in  order  to  be  placed  upon  the  negative, 
but  is  laid  upon  the  negative  in  the  dark  room. 

Supposing,  then,  all  is  ready  for  printing,  you  pro- 
ceed as  follows  : 

Lay  the  printing  frame  upon  a  flat  piece  of  wood, 
sufficiently  large  to  exclude  all  access  of  light  to  the 
negative  as  long  as  the  frame  thus  lies  in  apposition 
with  the  board.  Open  the  door  and  place  the  negative 
on  the  supporting  flanges,  the  film  being  upward  ;  dust 
the  film  with  a  broad  camel's  hair  pencil,  as  also  the 
tannin  film,  very  gently,  if  it  contain  any  small  particles, 


THE  TANNIN  PROCESS.  75 

The  tannin  plate  is  next  laid  down  upon  the  negative, 
the  two  films  being  in  contact ;  this  operation  must  be 
carefully  performed,  so  as  to  avoid  all  friction  which 
might  injure  the  tannin  film.  Place,  finally,  upon  the 
back  of  the  tannin  plate  a  piece  of  soft  yellow,  red,  or 
orange-colored  cloth,  and  close  the  door  with  the  press- 
ure springs.  The  orange-colored  cloth  is  intended  to 
destroy  all  effects  of  reflection  of  actinic  light  from  the 
posterior  surface  of  the  tannin  plate. 

The  next  operation  is  to  expose  the  plate  either  to 
solar  or  artificial  light.  Carry  the  frame,  supported  on 
the  thin  board,  out  of  the  dark  room  into  the  light,  as 
for  instance,  to  all  open  door  looking  to  the  north, 
where  diffused  light  alone  can  reach,  because  direct 
solar  light  is  much  too  powerful  and  unmanageable. 
Now  lift  up  the  printing  frame  from  the  board  and  ex- 
pose the  negative  to  the  sky  for  half  a  second,  a  second, 
or  more,  according  to  the  brightness  of  the  light  or  the 
density  of  the  negative.  Probably  an  exposure  for  one 
second  will  be  sufficient.  You  have  to  learn  the  length 
of  exposure  required  by  exposing  a  plate  or  two  ex- 
perimentally; afterward  you  can  judge  pretty  accurately 
as  to  the  exact  length  of  exposure  required  under  given 
circumstances.  The  printing  frame  is  again  laid  upon 
the  thin  board,  and  carried  back  again  into  the  dark 
room. 

The  treatment  of  the  plate  from  this  point  is  in  every 
respect  the  same  as  already  described  ;  the  plate  is 
simply  a  tannin  plate  already  exposed  and  ready  for 
development. 

But  the  exposure  can  be  effected  in  the  evening  and 
by  means  of  gaslight,  magnesium  light,  or  the  light 
from  a  piece  of  burning  phosphorus.  Where  gaslight 
is  available,  this  is  by  far  the  cheapest,  the  easiest,  and 
most  pleasant  to  operate  with  ;  and  because  it  is  not 


76 

so  rapid  in  its  action,  the  operation  is  much  more  man- 
ageable than  by  solar  diffused  light,  and  consequently 
the  operator  produces  better  results  with  such  an  ex- 
posure. 

The  gaslight  for  such  work  is  better  when  it  issues 
from  an  argand  burner,  and  is  surrounded  by  a  thin 
ground  glass  or  milk-white  globe  or  shade.  This  ar- 
rangement makes  the  light  uniform.  The  negative  is 
exposed  to  such  a  light  in  such  a  way  and  on  such  a  side 
or  position  where  there  is  no  object  to  produce  shadows. 
The  length  of  time  to  give  the  exposure  has  to  be  learned 
by  experience  ;  begin  with  eight  or  ten  seconds,  and 
try  a  few  plates  by  way  of  experiment.  From  the  fact 
that  any  amount  of  exposure  can  be  given  without  the 
slightest  detriment  to  the  picture,  the  acid  development 
is  always  to  be  recommended  in  preference  to  the  alka- 
line development. 

The  mode  of  operating  with  either  a  magnesium  or  a 
phosphorus  light  is  in  all  respects  the  same  as  with  a 
gaslight,  as  regards  the  exposure  ;  but  the  production 
of  the  light,  so  as  to  yield  the  best  effects,  depends  upon 
the  substance  used.  Magnesium  wire  or  coils  and  mag- 
nesium lamps  can  be  obtained  already  in  the  very  best 
conditions  for  producing  the  effect  require  I.  As  regards 
phosphorus,  few  have  ever  used  it.  We,  probably, 
were  the  first  to  recommend  its  use,  more  as  a  curiosity 
than  anything  else.  A  small  piece  of  phosphorus  of 
the  size  of  a  pea  is  lighted  on  a  piece  of  brick,  and 
while  burning  the  negative  is  exposed.  Such  a  piece 
will  generally  burn  long  enough  to  produce  the  requisite 
actinic  effect.  The  cloud  of  vapor  arising  from  the  ox- 
idation of  the  phosphorus  diminishes  or  clouds  the 
brilliancy  of  the  flame  ;  this  can  be  remedied  by  waving 
a  handkerchief  in  such  a  direction  as  to  produce  a  gentle 
draft  of  air,  so  as  to  drive  the  phosphoric  vapor  away 
from  the  exposed  plate. 


THE  TANNIN  PROCESS.  77 

We  have  also  obtained  very  good  results  with  a 
kerosene  lamp,  the  brilliant  flame  being  covered,  as 
was  the  case  with  the  gas  flame,  with  a  ground  glass 
shade  or  globe.  This  being  the  case,  it  is  evident  that, 
for  practical  operations  in  printing  on  glass  by  dry 
plates,  either  gaslight  or  kerosene  light  will  be  the 
most  convenient  and  the  least  expensive. 

To  print  stereoscopic  transparent  positives,  extra  in- 
struction has  to  be  given.  In  the  ordinary  negative, 
every  part  of  the  image  is  inverted,  right  is  left,  and  up 
is  down ;  but  the  effect  of  contact-printing,  either  on  glass 
or  paper,  rectifies  this  inversion,  and  places  the  figure 
in  its  right  position.  This  rectification  in  the  stereo- 
graph is  also^fcmplete  in  regard  to  each  picture  singly, 
but  the  right-hand  picture  by  printing  is  transferred  to 
the  left  side,  and  vice  versa.  From  this  fact  it  is  evi- 
dent that  a  common  stereoscopic  negative  can  not  be 
used  for  such  work.  How,  then,  are  we  to  proceed  ? 

There  are  two  ways  of  proceeding  in  order  to  put  the 
negative  in  a  right  position.  They  are  as  follows  : 

FIRST  METHOD. 

Cut  the  ordinary  stereoscopic  negative  in  two  through 
the  median  line.  Cut  off  from  the  right  side  of  the  right- 
hand  picture,  and  from  the  left  of  the  left-hand  picture, 
a  slip  of  glass,  so  as  to  make  either  negative  of  the 
same  size,  and  to  contain  the  same  amount  of  detail ;  a 
slip  of  glass  may  also  be  cut  off  from  the  top  and  bottom 
of  either  negative,  so  as  to  reduce  them  at  once  to  the 
regular  stereoscopic  size.  Having  made  these  excisions, 
invert  the  negatives,  and  place  the  right-hand  picture 
on  the  left  side,  and  vice  versa,  and  bring  the  middle 
edges  into  contact,  and  the  top  and  bottom  edges  into 
coincidence.  Fix  them  in  their  position,  on  a  piece  of 
well-cleaned  glass,  by  cementing  small  pieces  of  glass 


78  DRY  PLATE  PHOTOGRAPHY  J    OR, 

above,  below,  and  on  either  side,  so  as  to  hold  them 
from  changing  their  position.  They  are  now  in  a  con- 
dition to  be  printed  from. 

SECOND  METHOD. 

The  other  method  of  preparing  a  stereoscopic  neg- 
ative suitable  for  contact-printing,  is  somewhat  cir- 
cuitous, consisting,  first,  in  producing  a  transparent 
positive  of  the  negative,  by  means  of  the  camera  and 
two  lenses,  making  use  of  the  wet  process,  and  then 
obtaining  a  negative  from  the  positive  (in  which  all 
lateral  inversion  has  been  removed)  by  means  of  a 
camera  and  a  single  lens.  This  produces  a  negative  in 
the  right  condition.  We  will  now  desfjjfre  minutely 
the  two  operations  ;  they  require  great  nicety  of  ma- 
nipulation, and  are  very  instructive. 

We  suppose  the  reader  is  already  in  possession  of  a 
copying  camera,  which  consists,  or  may  consist,  of  two 
cameras  attached  firmly  together  endwise,  to  one  of 
which  is  screwed  a  lens  or  a  pair  of  lenses,  as  circum- 
stances require.  The  two  ground  glasses  are  placed 
four  times  the  focal  length  of  the  lens  or  lenses  apart, 
and  at  equal  distances  from  the  lens,  etc.  The  negative 
to  be  copied  is  placed  in  the  position  of  one  of  the  ground 
glasses,  and  the  sensitized  plate  is  placed  in  that  of  the 
other.  The  compound  camera  is  raised  and  inclined,  so 
as  to  receive  the  light  from  a  white  cloud  or  the  illumined 
sky  through  the  negative. 

For  the  operation  in  question  there  are  two  stero- 
scopic  lenses  fixed  in  the  end  of  one  of  the  cameras. 
The  negative  is  turned  wrong  side  up,  and  the  film 
looks  toward  the  lenses.  The  operation  of  focusing  is 
effected  by  sliding  backward  and  forward  the  body  of 
that  camera  which  is  to  contain  the  sensitized  plate. 
When  the  image  on  the  ground  glass  is  sharp  and  every- 


THE  TANNIN  PROCESS. 

where  well  defined,  measure  the  size  of  the  image  on 
the  ground  glass  and  compare  it  with  that  on  the  neg- 
ative ;  if  the  two  coincide  in  magnitude,  every  thing  is 
now  adjusted  ;  but  if  the  image  is  larger  on  the  ground 
glass,  draw  out  the  negative  slightly  and  push  in  the 
ground  glass,  until  the  desired  effect  is  produced.  When 
the  equi-distant  foci  are  once  found,  they  are  marked  on 
the  two  cameras  for  future  observation.  A  copy  is 
now  taken.  The  negative  as  it  stands  in  the  camera, 
with  the  collodion  film  looking  toward  the  lenses,  has 
the  following  appearance,  where  R  represents  the  right 
side  picture  and  L  the  left  picture,  both  facing  the 
observer  on  the  surface  of  glass  nearest  the  eyes. 


Negative  film  upward. 


The  effect  produced  by  copying  with  the  two  boxes 
is,  firstly,  to  produce  a  transparent  positive  ;  secondly, 
to  invert  each  picture  laterally,  so  that  the  appearance 
on  the  film  of  the  positive,  still  facing  the  spectator,  is 
as  follows  : 


Positive  film  upward. 


The  two  lenses  are  now  removed,  and  a  single  ortho- 
scopic  lens  placed  in  the  middle  in  their  stead  ;  and  the 
transparent  positive  takes  the  place  of  the  negative  in 
the  front  camera  facing  the  lens,  while  a  sensitized 
plate  is  placed  in  the  shield  of  the  camera.  An  im- 
pression is  now  taken,  which  will  be  a  negative,  in  a 
proper  condition  for  contact-printing  by  the  dry  pro- 
cess. The  position  of  the  two  images  on  the  film  be- 


80  DRY  PLATE  PHOTOGRAPHY  •    OR, 

hind  the  negative,  or  as  it  would  lie  on  paper  or  glass 
to  receive  the  rays  of  light  for  an  impression  would  be 
as  follows  : 


L 

R 

in  which  it  is  evident  that  the  right  picture  is  on  the 
right  side,  and  the  left  picture  on  the  left  side,  and 
not  inverted  vertically,  this  is  the  correct  position  ; 
but  it  will  be  observed,  that  the  impression  by  both 
methods  are  on  the  front  of  the  glasses,  which,  when 
mounted,  will  require  two  extra  plates,  a  translucent  or 
ground-glass  behind  and  a  transparent  one  in  front. 
These  glasses,  as  well  as  the  negative  plate,  are  as 
thin  as  possible  and  compatible,  nevertheless,  together 
they  appear  voluminous  and  heavy.  To  avoid  this 
bulk  and  weight  we  devise  means  by  which  the  positive 
picture  shall  be  beneath  the  plate,  and  still  in  its  true 
position  as  to  right  and  left.  This  can  be  effected 
either  from  the  cut  or  uncut  negative. 

Taking  the  cut  negative,  in  which  there  has  been  a 
transposition  of  the  two  pictures,  as  already  described 
for  the  first  method,  place  it  in  the  printing  frame  and 
take  an  impression  with  a  dry  plate,  which  will  be  a 
positive  ;  from  this,  the  film  looking  outward,  a  nega- 
tive is  taken  by  a  single  lens  by  the  wet  process.  The 
resulting  negative  will  produce,  by  contact,  a  positive 
print,  which  will  be  in  the  right  position  on  the  back  of 
the  plate ;  the  plate  itself,  therefore  protects  the  film 
from  injury  in  front,  while  the  ground  glass  protects  it 
behind.  The  different  forms  which  the  original  nega- 
tive undergoes  are  represented  by  the  following 
figure  : 


THE  TANNIN  PROCESS. 


81 


Original  negative,  film  upward,  or  in  front  of 
the  plate. 

Images  transposed  by  cutting  the  plate  in  two, 
film  in  front,  etc. 

Positive  by  contact,  film  behind  the  plate. 
Negative  by  one  lens,  film  behind  the  plate. 


A  second  method  to  accomplish  the  same  object  with 
the  cut  and  transposed  original  negative  is  as  follows  : 

Take  a  positive,  by  the  wet  process,  from  the  cut  and 
transposed  original  negative,  the  film  being  turned 
away  from  the  lens  ;  from  this  positive,  when  varnished, 
and  by  means  of  a  dry  tannin  plate,  take  a  negative  ; 
this  negative  will  be  in  a  proper  condition,  and  the 
pictures  will  be  similarly  located  as  by  the  preceding 
method.  The  figures  and  transformations  will  stand  as 
indicated  below : 


Original  negative,  film  upward. 

Images  transposed,  film  looking  ontward. 

Positive  taken  with  a  single  lens,  film  in 
front. 

Negative  by  contact-printing,  film  behind. 


But  the  same  result  can  be  obtained  more  easily  with- 
out cutting  the  glass  ;  more  easily,  because  the  glass 
is  not  required  to  be  cut.  There  are  two  methods  by 
which  this  end  can  be  obtained. 

In  the  first  place  let  the  film  of  the  original  negative 
look  outward  from  the  camera,  then  take  a  positive  by 
means  of  two  lenses  with  the  wet  process  ;  place  the 


82  DRY  PLATE  PHOTOGRAPfiY  ;    OR, 

positive  in  the  shield,  the  film  looking  inward,  and  take 
a  negative  with  one  lens.  The  various  configurations 
are  as  here  indicated  below  : 


Original  film  looking  outward. 

Positive  by  means  of  two  lenses,  film 
In  front. 

Negative  by  means  of  one  lens,  film 
behind. 

Secondly,  let  the  film  of  the  original  negative  be  out- 
ward, as  before,  and  take  a  transparent  positive  by  the 
wet  process  by  means  of  one  lens. 

Place  this  positive  in  the  shield,  the  film  looking  in- 
ward, and  by  means  of  two  lenses  and  the  wet  process 
take  a  negative  ;  it  will  be  exactly  similar  to  the  preced- 
ing, as  will  appear  from  the  configurations  : 


Film  of  original  negative  looking  outward. 
Positive  by  means  of  one  lens,  film  in  front. 


Negative  by  means  of  two  lenses,  film  be- 
hind. 


A  careful  attention  to  the  preceding  stereoscopic  forms, 
and  the  accompanying  text,  will  enable  any  photographer 
to  produce  stereoscopic  negatives  endowed  with  the 
necessary  conditions  for  the  preparation  of  glass  trans- 
parencies on  tannin  plates,  the  film  being  either  in  front 
of  the  glass  or  behind  it,  as  circumstances  require. 
Although  this  delightful  branch  of  photography  is  far 


THE  TANNIN  PROCESS.  83 

from  being  exhausted,  we  are  afraid  to  proceed  any  fur- 
ther, lest  the  patience  of  our  readers  become  exhausted. 
We  shall,  therefore,  proceed  at  once  to  the  next  chapter  ; 
for  we  suppose  the  mode  of  mounting  stereoscopic  trans- 
parencies requires  no  description  or  explanation. 


CHAPTER  VII. 

OPAL    OR   PORCELAIN    PICTURES    AND    PHOTO-MINIATURES 
BY  THE  DRY  PROCESS. 

THE  preparation  of  photographs  on  opal  or  porcelain 
plates  is  coming  daily  more  and  more  into  vogue  ;  and 
since  these  beautiful  pictures  can  be  prepared  quite  suc- 
cessfully on  dry  plates,  it  becomes  our  duty  to  give 
succinct  methods  of  performing  the  operation. 

There  are  several  ways  of  accomplishing  the  task  ; 
but  we  will  limit  ourselves  to  two,  which,  by  practice, 
are  known  to  be  successful ;  the  one  by  means  of  tan- 
nin plates,  and  the  other  by  the  collodio-chloride  process 
of  G.  Wharton  Simpson. 

OPAL  PICTURES  ON  TANNIN  PLATES. 

Porcelain  plates  with  ground  and  flat  surfaces  are 
alone  to  be  employed  in  this  department,  if  the  pictures 
are  to  be  obtained  by  contact-printing  ;  if  by  means  of 
the  conjugate  copying  camera,  the  ordinary  porcelain 
plate  may  be  used  instead.  In  either  case  the  plates, 
as  usual,  are  first  thoroughly  cleaned  and  polished,  and 
then  one  surface  is  flowed  with  pure  water,  and  after- 
ward with  the  albumen  solution  previously  described. 
In  all  other  respects  the  plates  undergo  the  same 
treatment  as  already  given  in  complete  detail  while 
describing  the  preparation  of  a  tannin  plate. 

The  ordinary  printing  frame  can  be  used  in  making 
these  glass  prints.  The  negative  and  dry  tannin  plate 
are  placed  in  contact,  and  the  dark  slide  behind  is  closed  ; 
and  either  a  mat  or  vignette  is  placed  over  the  negative 
in  order  to  circumscribe  the  picture.  All  the  precautions 


THE  TANNIN  PROCESS.  85 

squired  in  the  preparation  of  a  porcelain  picture  must 
e  observed  here  ;  thus,  the  hair  and  other  parts  of  the 
egative  may  be  too  transparent,  whereby  these  parts 
rould  be  much  sooner  printed  than  the  adjoining  half 
ints  or  dark  shades.  To  avoid  this  inequality  paper 
jrms  are  cut  out  which  cover  up  the  lightest  or  most 
ransparent  parts,  but  allow  the  light  to  pass  without 
iterruption  through  the  shades  and  halftones.  A  piece 
f  tissue  paper  may  cover  the  complete  opening.  The 
mgth  of  the  exposure  has  to  be  learned  by  practice  ; 
ry  a  few  seconds  with  a  free  exposure  to  a  white  cloud  ; 
without  the  paper  moderators  less  time  will  effect  the 
urpose. 

Either  the  acid  or  alkaline  developer  may  be  employed, 
loth  in  the  preparation  of  the  plates  and  in  the  process 
f  development,  fixing,  intensifying,  and  toning,  make 
se  of  every  precaution  to  avoid  any  cause  that  would 
roduce  stains.  Develop  until  the  picture  is  thoroughly 
rought  out ;  but,  above  all  things,  keep  the  lights  quite 
lear,  in  fact,  stop  in  all  cases  before  the  slightest  fogs 
st  in.  The  citro-pyrogallic  acid  is  to  be  preferred  as  a 
eveloper. 

Wash  and  fix  the  print  in  a  solution  of  hypo-sulphite 
f  soda,  and  again  thoroughly  wash. 

Now  examine  the  print  and  remove  all  particles,  of 
xtraneous  matter  from  the  picture,  by  means  of  the 
iiarp  point  of  a  stile  or  penknife  blade,,  and  wash  out 
le  stains  from  the  face  and  corners  of  the  plate  by 
-eating  them  first  with  a  solution  of  tincture  of  iodine 
i  water,  and  then  with  dilute  cyanide  of  potassium, 
e  careful  that  the  tincture  is  not  poured  on  any  part 
f  the  picture,  otherwise  the  markings  of  the  photograph 
rill  suffer.  The  most  persistent  stain  may  thus  be 
amoved  : 


86  DRY  PLATE  PHOTOGRAPHY  J  OR, 

TONING  OF  THE  OPAL  TANNIN  PICTURE. 

The  picture  being  bright,  sharp,  and  in  all  other  re- 
spects but  color  satisfactory,  the  next  operation  is  to 
communicate  to  it  the  desired  tone.  For  this  purpose 
make  the  following  solutions  : 

GOLD  SOLUTION. 

Na  L    j  Terchloride  of  gold  (£K£1S£)  •     1  grain. 
{ Distilled  or  rain  water      .  2  ounces. 


No.  1.  • 


MERCURY  SOLUTION. 

Of  a  saturated  solution  of  bi- 
chloride of  mercury        .         .       1  drachm. 


Citric  acid       ....  2  grains. 

Distilled  or  rain  water        .         .     10  ounces. 

The  film  being  well  washed  and  still  moist,  flow  it 
with  a  sufficient  quantity  of  the  gold  solution,  and  watch 
the  change  of  color  in  the  film.  This  color  will  be  a 
slate  blue  at  a  certain  point,  when  an  apparent  retro- 
grade action  sets  in,  and  the  intensity  becomes  gradu- 
ally less.  Wash  the  print  as  soon  as  you  think  the 
tone  begins  to  change  backward.  Now  flow  over  the 
film  a  drachm  or  two  of  the  mercury  solution.  This 
makes  the  shades  and  details  of  the  print  bright,  more 
black,  and  warmer  than  before.  In  fine,  by  this  pro- 
ceeding the  picture  will  be  so  far  complete. 

A  dilute  solution  of  nitric  acid — 20  drops  to  4  drachms 
of  water — is  sometimes  used  for  removing  stains  upon 
the  film,  and  thus  purifying  the  lights  or  whites.  Finally, 
the  film  is  washed,  dried,  colored,  and  varnished. 

PORCELAIN    PICTURES    BY    THE    COLLODIO-CHLORIDE     PROCESS 

SIMPSONTYPE. 

We  can  suggest  no  improvement  to  the  process 
practiced  by  our  friend,  H.  T.  Martin,  Esq.,  in  the 
preparation  of  porcelain  pictures  on  opal  glass. 


THE   TANNIN   PROCESS.  87 

The  porcelain  plates  are  ground  flat  on  one  surface, 
and  then  flowed  with  the  albumen  solution  already  de- 
scribed, and  put  away  to  dry. 

SENSITIVE  COLLODION. 

Ether  .....  1  ounce. 

Alcohol    ....  1  ounce. 

Pyroxyline  .                           .  12  grains  (»°£SiS'). 

Chloride  of  calcium           .  3  grains. 

Nitrate  of  silver  .         .         .16  grains. 

Citric  acid        ...  4  grains. 

Castor-oil     ....  4  drops. 

The  cotton  is  first  divided  into  small  tufts  and  then 
immersed  in  the  ether.  The  nitrate  of  silver  is  pulver- 
ized and  dissolved  in  the  smallest  possible  quantity  of 
water  ;  to  this  solution  add  two  or  three  drachms  of  the 
alcohol,  and  shake  the  mixture  intimately  and  put  aside 
for  a  moment. 

Add  the  remaining  part  of  the  alcohol  to  the  mixture 
of  ether  and  pyroxyline,  and  shake  the  mixture  until 
the  cotton  is  dissolved.  Pulverize  the  chloride  of  cal- 
cium and  dissolve  it  in  this  plain  collodion. 

Carry  these  two  solutions  into  the  dark  room,  and 
add  the  former  drop  by  drop  to  the  latter,  shaking  the 
mixture  well  after  each  addition.  An  emulsion  is  thus 
formed  by  the  double  decomposition  of  the  two  salts  in 
contact — nitrate  of  silver  and  chloride  of  calcium.  The 
fine  powder  of  chloride  of  silver,  intimately  diffused 
through  the  mixture,  gives  rise  to  this  emulsion,  which, 
with  the  collodion,  forms  the  sensitizing  vehicle  ;  it  is, 
in  fine,  the  sensitive  collodion. 

Finally,  add  the  four  drops  of  castor-oil,  and  set  the 
mixture  aside  for  a  day  or  two  to  settle.  By  the  end 
of  this  time  particles  of  undissolved  cotton  and  other 
matter  will  have  subsided.  The  fine  emulsion  is  de- 


88  DRY  PLATE  PHOTOGRAPHY  J   OR, 

canted  for  use.  It  must  be  preserved  in  the  dark  room 
and  kept  quite  excluded  from  the  light. 

The  castor-oil  is  introduced  in  order  to  permit  the 
process  of  printing  to  be  carried  on  to  any  extent  with- 
out any  risk  of  bronzing. 

Coat  the  dry  albumenized  plates  with  the  emulsion 
or  sensitized  collodion,  antl  allow  the  film  to  dry  com- 
pletely. When  dry  the  plates  are  fumed  for  about 
three  minutes  at  the  ordinary  temperature  ;  in  the  heat 
of  summer  less  fuming  will  be  sufficient.  After  this 
the  plates  arc  taken  out  from  the  fuming  chamber  and 
exposed  to  the  air  for  a  few  minutes.  They  are  now 
ready  for  exposure. 

The  negative  may  be  such  a  one  as  is  used  for  print- 
ing on  albumen  paper,  sharp  and  vigorous.  The  two 
plates,  the  negative  and  the  sensitive  plate,  are  placed 
with  their  two  films  in  perfect  contact  by  means  of 
Shive's  opal  printing  frames,  and  then  exposed  to  the 
light  of  the  sun.  This  frame  allows  the  operator  to  in- 
spect the  printing  as  it  proceeds.  Print  deeper  than  is 
ultimately  required,  because  the  intensity  is  somewhat 
diminished  in  the  subsequent  operations. 

TONING  THE  PORCELAIN   PICTURE. 

The  plate  is  gently  washed,  in  order  to  remove  all 
free  nitrate  of  silver  ;  it  is  then  immersed  in  an  old 
toning  bath,  or  flowed  with  a  dilute  solution  of  chloride 
of  gold,  as  already  described  in  the  preparation  of  porce- 
lain pictures  "on  tannin  plates,  and  afterward  with  the 
acid  and  dilute  solution  of  bi-chloride  of  mercury.  This 
latter  mode  will  be  found  an  advantage. 

The  plate  is  now  carefully  washed,  and  fixed  in  a 
bath  of  hypo-sulphite  of  soda  as  follows  : 

Hypo-sulphite  of  soda     ...       1  ounce. 
Water  10  ounces. 


THE  TANNIN  PROCESS.  89 

It  is  finally  washed  thoroughly  ;  all  stains  are  then 
removed  by  methods  already  given,  and  the  plate  is 
again  washed  and  dried.  The  picture  is  now  ready  for 
coloring  and  varnishing. 

THE  PREPARATION  OF  PHOTO-MICROGRAPHS  BY  MEANS  OF  TANNIN 
PLATES. 

The  camera  for  taking  photo-micrographs  is  furnished 
with  two  lenses,  one  for  taking  the  photograph  on  the 
sensitized  plate,  and  the  other  on  the  opposite  side  of 
the  ground-glass,  for  focusing  the  image.  The  lens 
proper  must  be  well  corrected,  and  have  a  focal  length 
of  a  quarter  of  an  inch  or  more.  The  objectives  made 
by  Grunow  for  his  microscopes  are  very  well  adapted 
for  the  preparation  of  photo-micrographs.  An  ordinary 
French  objective,  whose  focal  length  is  one  inch,  or  still 
better  a  Grunow's  one-inch  objective  will  be  suitable 
for  a  focusing  lens.  Both  these  lenses  are  fixed  per- 
pendicular on  opposite  sides  to  the  ground-glass,  and 
the  line  of  collimation  of  the  two  lenses  is  coincident. 
By  means  of  a  rack  and  pinion  motion  they  can  be 
brought  nearer  to  the  glass,  or  made  to  recede  from  the 
glass.  There  is  a  place  in  front  of  the  lens  proper  to 
receive  the  picture  to  be  copied  ;  the  shield  which  holds 
this  picture  is  vertical,  and  its  plane  parallel  with  the 
ground-glass. 

We  have  spoken  of  the  ground-glass  ;  we  mean,  how- 
ever, the  piece  of  polished  glass  which  takes  its  place  ; 
for  every  ground  surface,  when  viewed  by  the  focusing 
glass,  would  exhibit  ridges,  cavities,  and  mountains  of 
large  dimensions,  upon  which  no  microscopic  picture 
could  possibly  be  discerned.  The  surface  of  a  piece  of 
plate-glass  is  sufficiently  rough  for  this  delicate  opera- 
tion. 

The  first  step  to  be  taken  is  to  take  out  this  piece  of 


90  DRY  PLATE  PHOTOGRAPHY  ;  OR, 

plate-glass,  to  polish  it,  and  then  scatter  a  little  dust 
on  its  surface,  by  shaking  a  book  from  the  book-shelf 
close  by  it.  Although  no  dust  can  be  seen  by  the  naked 
eye,  you  will  find  sufficient  has  been  deposited  upon  the 
glass  when  it  is  examined  carefully  with  the  back  ob- 
jective. Now  bring  the  front  lens  into  its  place,  so 
that  it  illumines  a  small  circle  of  the  plate-glass  when 
it  is  pointed  to  the  sun's  rays  ;  whether  direct  or  after 
reflection.  We  know  that  the  line  of  collimation,  or  the 
axis  of  the  two  lenses  coincide,  from  the  fact  that  the 
illuminated  circle  of  light  produced  by  the  front  lens  is 
visible  by  the  focusing  glass. 

The  second  step  is  to  adjust  the  focusing  glass  itself 
to  focus.  This  is  accomplished  by  causing  the  lens  to 
approach  or  recede  from  the  plate  of  glass  until  the  fine 
particles  of  dust  on  the  surface  next  to  the  front  lens 
are  perfectly  well  defined.  This  adjustment  must  be 
made  with  the  utmost  accuracy.  It  is  evident  from  this 
arrangement,  that  if  there  were  a  picture  produced  by 
the  front  lens  on  the  surface  containing  the  dust,  it 
would  now  be  magnified  by  the  focusing  lens,  and  thus 
easily  distinguishable. 

The  third  step  is  to  place  the  negative  of  the  picture, 
photograph,  or  engraving  to  be  copied,  in  its  shield  be- 
fore the  front  lens,  and  to  illumine  this  with  the  bright 
rays  of  sunlight,  and  afterward  to  obtain  an  image  of 
this  picture  on  the  plate  of  glass.  This  is  done  by 
moving  the  lens  to  or  from  the  glass  until  the  picture 
is  quite  sharp  and  well  defined. 

These  photo-micrographic  cameras  are  generally  so 
constructed  as  to  take  a  number  of  photographs  on  the 
same  plates.  This  is  effected  by  sliding  the  plate-holder, 
by  means  of  a  graduated  rack  and  spring  eight  motions, 
for  instance,  horizontally,  and  vertically  by  the  same 
means  through  three  motions.  By  such  an  arrangement 


THE  TANNIN  PROCESS.  91 

twenty-four  photographs  can  be  taken  on  the  same 
plate.  The  slip  of  glass  to  receive  these  minute  photo- 
graphs is  very  thin.  It  is  treated  in  all  respects  like 
any  other  tannin  plate,  by  coating  it  first  with  albumen, 
then  with  collodion,  silver  solution,  and  tannin.  It  is 
afterward  dried,  when  it  is  ready  for  the  exposure.  A 
dry  plate  is  much  superior  to  a  wet  plate  for  this  pur- 
pose, because  it  allows  a  large  number  of  photographs 
to  be  taken  on  the  same  plate,  which  could  not  be  ef- 
fected by  the  wet  process,  from  the  drying  of  the  film. 
The  development,  fixing,  toning,  etc.,  do  not  vary  in  any 
point  from  what  has  already  been  minutely  explained. 
But  the  operator  will  need  a  pair  of  very  powerful 
spectacles  to  watch  the  development,  etc. 

When  the  transparent  positive  is  complete  and  dry,  it 
is  divided  up  by  a  diamond  into  separate  small  pictures, 
eacli  of  which  is  afterward  mounted  on  the  end  of 
a  Stanhope  lens  made  for  the  purpose.  The  slip  of 
glass  containing  the  picture  is  cemented  to  the  end  of 
the  lens  by  a  small  particle  of  Canada  balsam,  which 
melts  by  heat  ;  the  picture  is  laid  upon  the  melted 
balsam,  which,  on  cooling,  causes  the  glass  to  adhere 
with  great  firmness.  The  color  and  transparency  of 
the  balsam  are  indistinguishable  from  the  substance  of 
the  Stanhope  lens.  Such  photo-micrographs,  which  are 
too  small  for  the  naked  eye,  may  contain  a  copy  of  all 
the  illustrious  generals  of  our  country,  each  one  when 
magnified  by  the  lens  being  of  a  size  equal  to  that  of  a 
common  card-picture.  When  well  photographed,  such 
productions  seldom  fail  to  produce  the  liveliest  pleasure 
and  excite  wonder.  They  are  indeed,  although  toys, 
charming  productions. 


CHAPTER  VIII. 

DRY    AND     WET     PLATES     REQUIRING     NO     SILVER     BATH  ;      OR, 
NEGATIVE  PROCESSES  WITH  COLLODIO-BROMIDE  OF  SILVER. 

THE  processes  presented  in  this  chapter  we  have  not 
put  to  a  thorough  test  ourselves  ;  we  have  simply  tried 
them  and  obtained  pictures  by  them,  but  these  were  not 
so  intense  as  we  should  wish  them.  The  want  of  in- 
tensity, probably,  was  owing  to  some  omission  or  neg- 
lect on  our  part,  for  the  author  of  these  processes,  B. 
J.  Sayce,  says  he  has  experimented  upon  upward  of  two 
hundred  plates  without  making-  use  of  a  silver  bath, 
and  always  with  "unvarying  certainty  and  cleanliness, 
accompanied  by  a  considerable  saving*  of  labor,  time, 
and  expense  in  the  preparation  of  the  negatives/' 

PREPARATION  OF  THE  COLLODION. 

The  collodion  recommended  by  Mr.  Sayce,  and  which 
he  has  used  for  now  upward  of  two  years  and  a  half,  is 
prepared  as  follows  : 

Bromide  of  cadmium  .  .  .60  grains. 
Bromide  of  ammonium  .  .  20  grains. 
Pyroxyline  .  .  .  .  .60  grains. 

Ether 5  ounces. 

Alcohol 5  ounces. 

Prepare  this  plain  collodion  in  the  above  proportions, 
in  any  quantity  desired,  and  put  it  aside  for  a  number 
of  days  to  settle  ;  then  decant,  or  filter  when  required 
for  use. 

Now,  take  of  nitrate  of  silver,  in  crystals,  120  grains, 


THE  TANNIN  PROCESS.  93 

and  reduce  the  salt  to  an  impalpable  powder  in  a  mor- 
tar ;  finally,  dissolve  it  in  the  smallest  quantity  of  water, 
and  mix  with  the  above  quantity  of  collodion,  in  a  dark 
room,  stirring  the  mixture  all  the  while  as  the  silver 
solution  is  poured  into  the  collodion.  The  mixture  is 
then  shaken  up  intimately,  and  put  in  a  dark  cupboard 
to  settle. 

In  the  course  of  an  hour  or  two  the  clear  or  fine 
emulsion  on  the  upper  portion  is  decanted  off  and  is 
ready  for  use. 

WET  PROCESS  WITH  THE  COLLODIO-BROMIDE  OF  SILVER. 

The  edges  of  the  plates  to  be  used  are  first  varnished 
either  with  a  solution  of  one  grain  of  india-rubber  dis- 
solved in  one  ounce  of  benzine,  or  with  the  albumen 
solution  recommended  in  the  previous  chapters  for  giving 
to  tannin  plates  a  substratum  previous  to  the  collodion 
film.  A  safer  plan  will  be  to  use  the  substratum  as  re- 
commended by  us,  and  when  the  plates  are  dry,  to  flow 
them  with  the  collodio-bromide  in  the  usual  way.  As 
soon  as  the  film  has  set  sufficiently,  the  plate  is  placed 
in  a  dish  of  water  until  the  greasy  appearance  has 
vanished.  Warm  water  is  preferable,  because  it  is 
quicker  in  its  action,  and  the  heat  renders  the  film  more 
sensitive.  When  the  water  flows  freely  over  the  film, 
the  plate  is  withdrawn  from  the  dish  or  bath,  and 
allowed  to  drain  a  moment  or  two  ;  the  back  is  then 
wiped  with  a  clean  cloth  ;  and  the  plate  is  inverted  in 
the  plate-holder  and  exposed.  The  exposure  is  some- 
what longer  than  that  required  by  the  ordinary  wet 
process. 

DEVELOPMENT  OF  THE  COLLODIO-BROMIDE  FILM. 

Take  the  plate  from  its  shield  in  the  dark  room,  ancj 
moisten  the  film  with  a  little  water. 

4* 


94 


DEVELOPER. 


Proto-sulphate  of  iron  .  .  ,.  100  grains. 
Glacial  acetic  acid  .  .  .  100  grains. 
Water 4  ounces. 

To  three  drachms  of  this  solution,  add  two  drops  of  a 
solution  of  nitrate  of  silver,  containing  twenty  grains 
to  the  ounce  of  distilled  water. 

The  image  appears  quickly,  and  in  every  respect 
similar  to  that  produced  by  a  negative  according  to  the 
ordinary  wet  collodion  process. 

The  picture  is  afterward  intensified  by  any  of  the 
methods  already  known. 

FIXING  THE  IMAGE. 

Prepare  a  solution  of  cyanide  of  potassium  as  follows  : 

Cyanide  of  potassium  .  .  .  100  grains. 
Water 5  ounces. 

Immerse  the  washed  plate  in  this  solution,  which  will 
soon  dissolve  off  the  unaffected  bromide  of  silver.  When 
the  substratum  is  albumen,  it  is  our  opinion  that  the 
hyposulphite  fixing  solution  will  be  preferable. 

DRY  PROCESS  WITH  THE  COLLODIO-BROMIDE  OF  SILVER. 

The  plates  are  previously  prepared,  either  with  an 
india-rubber  solution  round  the  edges,  or  with  an  albu- 
men solution,  as  recommended  in  the  preceding  wet 
process.  Each  plate  is  then  coated  in  the  dark  room 
with  the  collodio-bromide,  and,  when  the  film  has  set 
sufficiently,  it  is  immersed  in  a  dish  or  pail  of  water  ; 
in  this  way  proceed  with  all  the  plates. 

Having  a  dish  filled  with  hot  water,  as  hot  as  the 
hand  can  bear,  take  out  each  plate  in  rotation  and  im- 
merse it  in  the  bath  for  about  thirty  seconds,  and  after- 
ward in  the  tannin  solution,  containing  15  grains  to 


THE   TANNIN   PROCESS.  95 

the  ounce  of  water,  well  filtered,  or  in  the  following  solu- 
tion, which  Mr.  Sayce  finds  superior  to  the  preceding  : 

Tannin 100  grains. 

Gallic  acid      ....          50  grains. 

Water 10  ounces. 

Grape  sugar  .         .         .         .  50  grains. 

Alcohol  .....  100  minims. 
Dissolve  the  tannin  in  one  portion  of  the  water  and 
filter  ;  dissolve  the  gallic  acid  by  heat  in  another  portion, 
and,  when  filtered,  mix  it  with  the  tannin  ;  then  add  the 
grape  sugar  and  filter  once  more  ;  finally,  the  alcohol  is 
added,  and  the  bath  is  ready  for  use. 

If  the  plate  is  allowed  to  remain  in  the  above  solu- 
tion for  three  minutes,  after  a  proper  exposure,  very 
little  or  no  intensification  at  all  is  necessary. 

After  immersion  in  the  tannin  bath,  each  plate  is 
taken  out,  allowed  to  drain,  and  then  dried  evenly  and 
quickly  in  any  convenient  and  suitable  manner.  The 
steam  chamber  recommended  in  a  previous  chapter,  may 
be  used  here  with  advantage. 

Mr.  Sayce  asserts  that  the  exposure  of  a  collodio- 
bromide  plate  is  one  half  shorter  than  that  required  by 
a  bromo-iodized  plate. 

DEVELOPMENT  OF  THE  COLLODIO-BROMIDE  PLATE. 

Prepare  the  following  solutions  : 
jr      «     f  Alcohol         .        .        .        .       2  ounces. 
I  Distilled  or  rain  water      .          2  ounces. 

No   2    -f  ^ar^onate  °f  ammonia          .     40  grains. 
1  Distilled  or  rain  water      .        20  ounces. 

j-      o    ( Pyrogallic  acid     .        .    <     .     96  grains. 
( Absolute  alcohol       .        .          1  ounce. 

^r      *     ( Bromide  of  potassium   .        .40  grains. 
1  Distilled  or  rain  water  4  ounces. 


96 

f  Nitrate  of  silver   .        .        .30  grains. 
No.  5.  \  Citric  acid          ...         15  grains. 
[  Distilled  or  rain  water          .       1  ounce. 

Pour  a  sufficient  quantity  of  No.  1  upon  the  exposed 
film,  so  as  to  cover  it,  and  then  return  it  into  the  bottle 
for  future  use.  Then  place  the  plate  in  a  dish  of  clean 
water  and  move  it  about  gently  until  the  oily  appear- 
ance has  vanished.  Now  prepare  the  following  mixture  : 
No.  2  .....  4  drachms. 

No.  3 3  drops. 

No.  4 2  drops. 

Shake  up  the  mixture  well,  and  then  pour  it  over  the 
plate,  and  keep  the  solution  in  motion.  The  image 
ought  to  appear  very  soon,  and  may  be  developed  until 
the  shadows  become  slightly  tinged.  The  plate  is  now 
thoroughly  washed  with  water  on  both  sides,  and  after- 
ward with  a  dilute  solution  of  acetic  acid,  2  drops  of 
glacial  acetic  acid  to  1  ounce  of  water. 

The  picture  is  afterward  intensified  by  flowing  it  with 
the  following  solution : 

No.  3    .         .         .         .         .         .3  minims. 

No.  5        .....         3  minims. 

Water  ......     ?  drachms. 

When  the  shades  are  sufficiently  dense,  the  plate  is 
again  well  washed  and  immersed  in  the  fixing  bath  recom- 
mended for  the  wet  process.  It  is  finally  washed  thor- 
oughly and  set  aside  to  dry.  The  author  of  the  process 
says  that  a  strong  solution  of  the  cyanide  of  potassium 
is  preferable  to  a  weak  solution,  which  has  a  tendency 
to  cause  the  film  to  split  up  on  drying.  As  before  re- 
marked, we  should  prefer  the  use  of  the  hyposulphite 
fixing  solution  in  this  process,  but  have  not  the  experi- 
ence to  assert  that  it  is  decidedly  better. 

And  now,  dear  reader,  we  have  finished  the  task  im- 


THE  TANNIN   PROCESS.  91 

posed  upon  ourselves.  It  is  to  be  hoped  the  work  will 
be  found  useful  to  you  in  many  ways,  because  the  in- 
struction communicated  is,  in  general,  of  a  very  varied 
character  and  the  result  of  successful  practice. 

In  a  month  or  two  you  will,  Deo  volente,  hear  again 
from  us  ;  there  is  no  possibility  of  satisfying  our  pub- 
lisher ;  he  is  ever  crying  out,  viva  voce  or  by  letter  : 
"More,  more,"  and  as  long  as  we  have  a  laboratory  to 
work  in,  brains  to  concoct,  and  fingers  to  write,  you 
may  expect  "  more,  more,"  and  we  hope  you  may  remain 
in  the  condition  of  our  publisher,  ever  craving  after 
fresh  food,  but  never  satisfied.  A  dios! 


ADVERTISEMENTS. 


HUMPHREY'S  COLLODION  GILDING. 


ONE  OF  THE  MOST  VALUABLE  IMPROVEMENTS  since  the  application  of  the  Col- 
lodlon  FHm  as  a  vehicle  of  producing  Photographic  Images,  is  HUMPHREY'S  COLLO- 
DION GILDING.  It  is  a  rare  discovery,  and  is  being  rapidly  brought  into  use  l»y  the 
first  Ambrotypers  and  Photographers  in  America.  It  adds  at  least  one  half  to  the  beauty 
of  an  Ambrotype,  above  any  method  heretofore  in  use. 

It  Is  IMPKRISHABLE,  as  it  gives  a  surface  almost  equal  in  Hardness  to  th.it  of  the  Glass 
tself.  It  is  Easy  of  Application,  gives  a  Brilliant  finish,  and  is  not  affected  by  Moist 
Atmosphere,  nor  by  Pure  Water.  It  is  the  best  article  ever  used  for  FINISHING  Pictures. 
.t  preserves  Positives  and  Negatives  from  injury  by  Light,  and  will  preserve  Glass  Nega- 
1***  for  *U  time.  It  gives  &  rich  lustre  to  Drapery,  and  will  bear  exposure  in  the  hot  sun. 

CERTIFICATES. 

From  JAKES  R.  CHILTON,  M.D.,  the  well-known  Chemist. 

NEW-York,  April  6th,  1S62. 

1  nave  experimented  upon  a  sample  of  "  Humphrey's  Collodion  Gilding,"  and  find 
the  nature  of  its  composition  to  be  such  as  to  render  it  a  very  desirable  article.  It 
will  answer  the  requirements  of  a  transparent,  durable  Varnish  for  protecting  Collo- 
dion Pictures  better  than  any  other  preparation  I  am  acquainted  with. 

JAMES  R.  CHILTON,  M.D.,   Chemist. 

NEW-YORK,  March  8 1st. 

DEAR  SIR:  Having  found  "Humphrey's  Collodion  Gilding,"  as  prepared  by  you,  to 
meet  every  requirement,  I  will,  at  all  times,  take  pleasure  in  recommending  it  to  my 
brother  photographers  as  the  best  article  for  preserving  Glass  Negatives  aijd  Ambrotypes. 
Wishing  you  the  success  you  so  justly  deserve,  I  remain  Your  obedient  servant, 

J.  GUKNEY. 


NEW- YORK.  April  6th. 

DBAR  SIR:  I  have  given  "  Humphrey's  Collodion  Gilding"  a  trial,  and 'find  it  better 
than  any  of  the  varnishes  I  have  before  used.  I  take  pleasure  in  recommending  it  to 
others  at  one  of  the  most  desirable  articles  for  preserving  Glass  Pictures,  and  as  being 
fully  worthy  of  their  confidence.  Yours  truly,  M.  M.  LAWRENCE. 

CANANDAIGUA,  N.  Y.,  April  Sth. 

DEAR  SIR  :  "  Humphrey's  Collodion  Gilding  "  settles  the  long-contested  point  sis  to 
the  durability  of  collodion  pictures.  I  consider  it  not  only  the  best,  but  the  only  perfect 
protection  and  finish  for  the  surface  of  the  collodion  plate,  whether  positive  or  negative. 

Respectfully  yours,  M.  FIN  LEY. 

DEAR  SIR:  We  would  say  that  the  sample  of  "Humphrey's  Collodion  Gilding"  which 
you  furnished  us  with  has  given  entire  satisfaction,  and  we  do  -unhesitatingly  pronounce 
It  the  best  article  we  have  ever  used  for  the  Protection  of  Glass  Negatives  and  Positives. 
Respectfully  yours,  SILSBEE,  CASE  &  CO., 

299*  Washington  Street,  Boston. 

ALBANY,  N.  Y.,  March  '2 1st. 

DEAR  SIR:  For  some  time  past  I  have  used  " Humphrey's  Collodion  Gilding"  with 
the  most  eminent  success,  and  in  no  instance  have  had  caus  to  complain ;  but,  on 
the  contrary,  find  it  all  that  it  has  been  represented.  Your  "recently  improved  "  manu- 
facture surprises  me,  for  I  did  not  think  it  possible  for  any  improvement  to  be  made  over 
that  I  was  using.  Please  forward  half-a-dozen  bottles  without  delay;  Icannot  afford 
to  be  without  it  in  my  establishment.  Truly  yours,  etc.,  S.  J.  THOMPSON. 

"  Humphrey's  Collodion  Gilding  "  is  the  best  Varnish  I  ever  used,  and  I  have  tried 
all  kinds.  J.  F.  RYDER. 

It  is  the  best  article  known  to  preserve  Ambrotypes  or  Negatives.— W.  M.  GARDNER. 
It  is  the  best  article  I  ever  used.    I  consider  it  imperishable.— C.  W.  GREY. 
I  am  pleased  with  it.    I  put  up  no  pictures  without  it.— L.  W.  KEEN. 

It  is  the  only  varnish  that  is  suitable  for  Melainotypei ;  I  have  tried  all  others  in 
market.  W.  11.  DE  SHONG. 

I  am  pleased  with  Humphrey's  Collodion  Gilding.  I  exposed  a  glass  picture  finished 
with  It,  on  a  roof  facing  the  sun,  for  one  week,  to  the  combined  influence  of  the  hot  sun,  a 
•evere  snow-storm,  rain,  and  two  hard  frosts,  one  of  them  while  it  was  covered  up  \vlth 
snow,  and  it  kept  bright  as  at  first.  C.  G.  G1LLETT. 

Put  up  la  Six  Ounce  Bottles.    For  Sale  by  all  Stock  Dealer* 


VALUABLE  PHOTOGRAPHIC  BOOKS!! 

SENT  PREPAID  OK  RECEIPT  OF  FRIGE. 

The  Silver  Sunbeam.  Fourth  Edition.  By  Prof.  Towler. 
The  best  work  on  Photography  ever  issued.  12mo,  400 
pages.  Price,  $2.50. 

The  Porcelain  Picture.  With  Instructions  How  to  Make 
it.  By  Prof.  Towler.  12mo.  Price,  $1. 

The  American  Photographic  Almanac  for  1S66.  By 
Prof.  Towler.  12mo,  100  pages.  Price,  50  cents. 

The  American  Photographic  Almanac  for  1865.  Price, 
50  cents. 

Dry  Plate  Photography;  or,  The  Tannin  Process  made 
Simple  and  Practical  for  Operators  and  Amateurs.  By 
John  Towler,  M.  D.  100  pages.  Price,  $1. 

Practical  Manual  of  the  Collodion  Process,  giving  a 
Method  for  Producing  Positive  and  Negative  Pictures 
on  Glass  and  Paper.  By  S.  D.  Humphrey.  Price, 
50  cents. 

Photography  on  Collodion.     150  pages.    $1. 

The  Carte  de  Visite  Process.  With  full  and  explicit 
Directions  for  Taking  Card  Pictures  and  Vignettes. 
Price,  50  cents. 

Hunt's  Treatise  on  Photography.  Illustrated.  Giving 
full  Details  of  the  Calotype,  and  other  valuable  processes. 
By  Robert  Hunt.  266  pages.  Price,  $1.  ( 

Practical  Photography  on  Glass  and  Paper.  With 
positive  Rules  for  Obtaining  Intense  Negatives  with  Cer- 
tainty. By  F.  B.  Gage.  Only  a  few  left.  Price,  $1. 

The  Daguerreotype  Operator.  A  Practical  Work,  con- 
taining the  Most  Approved  Methods  of  Producing  these 
Pictures.  Price,  30  cents. 

Humphrey's  Journal  of  Photography.  Back  volumes 
Two  Dollars  each.  Last  year's  volume,  Three*  Dollars. 
A  most  invaluable  collection  of  Photographic  literature, 
such  as  can  be  had  in  no  other  form. 

All  the  above  sent  post  paid  on  receipt  of  price.     Address 

JOSEPH  H.  LADD, 

Photographic  Book  Publisher, 

P.  O.  Box  34UO,  NKVV  YORK. 


JOSEPH  H.   LADD 

NEW-YO» 


li  slier, 


UNIVERSITY  OF  CALIFORNIA  LIBRARY 
BERKELEY 

Return  to  desk  from  which  borrowed. 
This  book  is  DUE  on  the  last  date  stamped  below. 


REC'D  LD 

JAN  17 '64-0  AM 


U69    1957 

*I(MOT-Sr,'48  (B399sl6)476 

JUL  1 S 1985 


YB   I  M  35 

GENERAL  LIBRARY  -  U.C.  BERKELEY 


BDOOfllbOSl 


M542349 


